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1.  A Statistical Model of the International Spread of Wild Poliovirus in Africa Used to Predict and Prevent Outbreaks 
PLoS Medicine  2011;8(10):e1001109.
Using outbreak data from 2003–2010, Kathleen O'Reilly and colleagues develop a statistical model of the spread of wild polioviruses in Africa that can predict polio outbreaks six months in advance.
Outbreaks of poliomyelitis in African countries that were previously free of wild-type poliovirus cost the Global Polio Eradication Initiative US$850 million during 2003–2009, and have limited the ability of the program to focus on endemic countries. A quantitative understanding of the factors that predict the distribution and timing of outbreaks will enable their prevention and facilitate the completion of global eradication.
Methods and Findings
Children with poliomyelitis in Africa from 1 January 2003 to 31 December 2010 were identified through routine surveillance of cases of acute flaccid paralysis, and separate outbreaks associated with importation of wild-type poliovirus were defined using the genetic relatedness of these viruses in the VP1/2A region. Potential explanatory variables were examined for their association with the number, size, and duration of poliomyelitis outbreaks in 6-mo periods using multivariable regression analysis. The predictive ability of 6-mo-ahead forecasts of poliomyelitis outbreaks in each country based on the regression model was assessed. A total of 142 genetically distinct outbreaks of poliomyelitis were recorded in 25 African countries, resulting in 1–228 cases (median of two cases). The estimated number of people arriving from infected countries and <5-y childhood mortality were independently associated with the number of outbreaks. Immunisation coverage based on the reported vaccination history of children with non-polio acute flaccid paralysis was associated with the duration and size of each outbreak, as well as the number of outbreaks. Six-month-ahead forecasts of the number of outbreaks in a country or region changed over time and had a predictive ability of 82%.
Outbreaks of poliomyelitis resulted primarily from continued transmission in Nigeria and the poor immunisation status of populations in neighbouring countries. From 1 January 2010 to 30 June 2011, reduced transmission in Nigeria and increased incidence in reinfected countries in west and central Africa have changed the geographical risk of polio outbreaks, and will require careful immunisation planning to limit onward spread.
Please see later in the article for the Editors' Summary
Editors' Summary
During the first half of the 20th century, polio (poliomyelitis) was one of the most feared infectious diseases in industrialized countries, paralyzing thousands of young children every year. The virus that causes polio enters the human body through ingestion of contaminated water or food, multiplies in the gut, and is shed through the feces (stool) into the environment, where it spreads rapidly if sanitation or personal hygiene is poor. Most people infected with poliovirus have no symptoms, but about one in 200 infected people develop paralytic polio, in which poliovirus invades and destroys the nerve cells that control the arm and leg muscles, leading to acute flaccid paralysis (AFP; limb paralysis). In the worst cases, poliovirus paralyzes the muscles involved in breathing, which can be fatal unless patients are helped to breathe with an “iron lung” or ventilator. There is no cure for paralytic polio, and although AFP usually lasts less than two weeks, some patients never regain full use of their limbs.
Why Was This Study Done?
From 1955 onwards, routine polio vaccination rapidly reduced or eliminated wild polio (polio occurring through natural infection) in developed countries, but the disease remained common in developing countries. Consequently, in 1988, the Global Polio Eradication Initiative was launched. Between 1988 and 2009, routine vaccination and supplementary immunization activities (additional doses of polio vaccine given to all young children on national immunization days) reduced the annual number of children paralyzed by polio from 350,000 to about 1,600 and the number of countries where polio is endemic (always present) from 125 to four. Unfortunately, continued circulation of wild polioviruses in Nigeria and India resulted in reinfection of 19 African countries in 2009 and re-establishment of polio transmission in four countries. A better understanding of the factors that affect the distribution and timing of wild polio outbreaks might help experts prevent such outbreaks and could facilitate global polio eradication. Here, the researchers develop a statistical model of the spread of wild polioviruses in Africa and assess its ability to predict polio outbreaks in individual African countries.
What Did the Researchers Do and Find?
The researchers used routine AFP surveillance to identify children who developed polio in Africa between 2003 and 2010. They determined whether each case was associated with the importation of wild poliovirus based on genetic analysis the polioviruses and then used “multivariable regression analysis” to identify factors associated with the number, size, and duration of polio outbreaks. During the study period, 142 genetically distinct polio outbreaks (involving one to 228 cases) were recorded in 25 African countries, with the average number of outbreaks in each country declining with reduced population movements from each infected country. The estimated number of people migrating into a country from an infected country was associated with the number of outbreaks in that country. Thus, countries with a high rate of immigration from Nigeria and other countries where polio is still endemic had more polio outbreaks than countries with less immigration from these countries. A country's mortality rate for children under 5 years of age (an indicator of sanitary conditions and access to health care) was also associated with the number of outbreaks, and immunization coverage was associated with the size, duration, and number of outbreaks. Finally, in 82% of instances, for a randomly selected country where an outbreak was observed, the statistical model predicted six months ahead of time more outbreaks for that country than for any randomly selected country where there were no outbreaks. That is, the model's predictive ability was 82%.
What Do These Findings Mean?
These findings indicate that outbreaks of polio in Africa over the study period resulted mainly from continued transmission in Nigeria and other countries that reported polio cases and from poor immunization status. They also highlight how the geographical risk of polio is changing over time in Africa. Importantly, the risk factors included by the researchers in their statistical model are sufficient to describe the scale and geographical distribution of polio outbreaks in Africa six months in advance with a high predictive ability. Although the accuracy of the predictions made by the model is limited by the structure of the model and by the data fed into it, the information provided by this and other predictive models should help the Global Polio Eradication Initiative plan its future immunization and surveillance campaigns and should facilitate the elimination of polio from Africa.
Additional Information
Please access these websites via the online version of this summary at
The Global Polio Eradication Initiative provides information about polio and about global efforts to eradicate the disease; its website includes links to videos about global polio elimination efforts
The World Health Organization provides information about polio and attempts to eradicate the disease (in several languages)
The US Centers for Disease Control and Prevention provides information about polio vaccination
The UK National Health Service Choices website has information on polio
MedlinePlus provides links to more resources on polio (in English and Spanish)
Personal stories about polio are available through the British Polio Fellowship Heritage Project; the National Museum of American History Whatever happened to polio? website includes an archive of polio-related pictures
PMCID: PMC3196484  PMID: 22028632
2.  Performance and determinants of routine immunization coverage within the context of intensive polio eradication activities in Uttar Pradesh, India: Social Mobilization Network (SM Net) and Core Group Polio Project (CGPP) 
Studies that have looked at the effect of polio eradication efforts in India on routine immunization programs have provided mixed findings. One polio eradication project, funded by US Agency for International Development (USAID) and carried out by the CORE Group Polio Project (CGPP) in the state of Uttar Pradesh of India, has included the strengthening of routine immunization systems as a core part of its polio eradication strategy. This paper explores the performance of routine immunization services in the CGPP intervention areas concurrent with intensive polio eradication activities. The paper also explores determinants of routine immunization performance such as caretaker characteristics and CGPP activities to strengthen routine immunization services.
We conduct secondary data analysis of the latest project household immunization survey in 2011 and compare these findings to reports of past surveys in the CGPP program area and at the Uttar Pradesh state level (as measured by children’s receipt of DPT vaccinations). This is done to judge if there is any evidence that routine immunization services are being disrupted. We also model characteristics of survey respondents and respondents’ exposure to CGPP, communication activities against their children’s receipt of key vaccinations in order to identify determinants of routine immunization coverage.
Routine immunization coverage has increased between the first survey (2005 for state level estimates, 2008 for the CGPP program) and the latest (2011 for both state level and CGPP areas), as measured by children’s receipt of DPT vaccination. This increase occurred concurrent with polio eradication efforts intensive enough to result in interruption of transmission. In addition, a mothers’ exposure to specific communication materials, her religion and education were associated with whether or not her children receive one or more doses of DPT.
A limitation of the analysis is the absence of a controlled comparison. It is possible routine immunization coverage would have increased even more in the absence of polio eradication efforts. At the same time, however, there is no evidence that routine immunization services were disrupted by polio eradication efforts. Targeted health communications are helpful in improving routine immunization performance. Strategies to address other determinants of routine immunization, such as religion and education, are also needed to maximize coverage.
PMCID: PMC3658862  PMID: 23680228
3.  Eradicating poliomyelitis: India's journey from hyperendemic to polio-free status 
India's success in eliminating wild polioviruses (WPVs) has been acclaimed globally. Since the last case on January 13, 2011 success has been sustained for two years. By early 2014 India could be certified free of WPV transmission, if no indigenous transmission occurs, the chances of which is considered zero. Until early 1990s India was hyperendemic for polio, with an average of 500 to 1000 children getting paralysed daily. In spite of introducing trivalent oral poliovirus vaccine (tOPV) in the Expanded Programme on Immunization (EPI) in 1979, the burden of polio did not fall below that of the pre-EPI era for a decade. One of the main reasons was the low vaccine efficacy (VE) of tOPV against WPV types 1 and 3. The VE of tOPV was highest for type 2 and WPV type 2 was eliminated in 1999 itself as the average per-capita vaccine coverage reached 6. The VE against types 1 and 3 was the lowest in Uttar Pradesh and Bihar, where the force of transmission of WPVs was maximum on account of the highest infant-population density. Transmission was finally interrupted with sustained and extraordinary efforts. During the years since 2004 annual pulse polio vaccination campaigns were conducted 10 times each year, virtually every child was tracked and vaccinated - including in all transit points and transport vehicles, monovalent OPV types 1 and 3 were licensed and applied in titrated campaigns according to WPV epidemiology and bivalent OPV (bOPV, with both types 1 and 3) was developed and judiciously deployed. Elimination of WPVs with OPV is only phase 1 of polio eradication. India is poised to progress to phase 2, with introduction of inactivated poliovirus vaccine (IPV), switch from tOPV to bOPV and final elimination of all vaccine-related and vaccine-derived polioviruses. True polio eradication demands zero incidence of poliovirus infection, wild and vaccine.
PMCID: PMC3734678  PMID: 23760372
EPI; eradication; polio; vaccine; wild polioviruses
4.  Determinants of vaccination coverage in rural Nigeria 
BMC Public Health  2008;8:381.
Childhood immunization is a cost effective public health strategy. Expanded Programme on Immunisation (EPI) services have been provided in a rural Nigerian community (Sabongidda-Ora, Edo State) at no cost to the community since 1998 through a privately financed vaccination project (private public partnership). The objective of this survey was to assess vaccination coverage and its determinants in this rural community in Nigeria
A cross-sectional survey was conducted in September 2006, which included the use of interviewer-administered questionnaire to assess knowledge of mothers of children aged 12–23 months and vaccination coverage. Survey participants were selected following the World Health Organization's (WHO) immunization coverage cluster survey design. Vaccination coverage was assessed by vaccination card and maternal history. A child was said to be fully immunized if he or she had received all of the following vaccines: a dose of Bacille Calmette Guerin (BCG), three doses of oral polio (OPV), three doses of diphtheria, pertussis and tetanus (DPT), three doses of hepatitis B (HB) and one dose of measles by the time he or she was enrolled in the survey, i.e. between the ages of 12–23 months. Knowledge of the mothers was graded as satisfactory if mothers had at least a score of 3 out of a maximum of 5 points. Logistic regression was performed to identify determinants of full immunization status.
Three hundred and thirty-nine mothers and 339 children (each mother had one eligible child) were included in the survey. Most of the mothers (99.1%) had very positive attitudes to immunization and > 55% were generally knowledgeable about symptoms of vaccine preventable diseases except for difficulty in breathing (as symptom of diphtheria). Two hundred and ninety-five mothers (87.0%) had a satisfactory level of knowledge. Vaccination coverage against all the seven childhood vaccine preventable diseases was 61.9% although it was significantly higher (p = 0.002) amongst those who had a vaccination card (131/188, 69.7%) than in those assessed by maternal history (79/151, 52.3%). Multiple logistic regression showed that mothers' knowledge of immunization (p = 0.006) and vaccination at a privately funded health facility (p < 0.001) were significantly correlated with the rate of full immunization.
Eight years after initiation of this privately financed vaccination project (private-public partnership), vaccination coverage in this rural community is at a level that provides high protection (81%) against DPT/OPV. Completeness of vaccination was significantly correlated with knowledge of mothers on immunization and adequate attention should be given to this if high coverage levels are to be sustained.
PMCID: PMC2587468  PMID: 18986544
5.  The response to oral poliovaccine in persons aged 16-18 years. 
The Journal of Hygiene  1976;76(2):235-247.
Serum neutralizing antibodies to polioviruses were titrated in serum samples from 182 police cadets aged 16-18 years before and, in 168 of the cadets, 6 weeks after vaccination with a single dose of oral polio vaccine (OPV). Faecal excretion of poliovirus was also followed. Vaccination histories were obtained and confirmed whenever possible. Pre-vaccination antibody could not be detected against type 1 in 9-3% cadets, against type 2 in 2-7% and against type 3 in 7-7%. Absence of antibody to at least one virus type was found in 14-3% of the cadets. In 93 cadets in whom vaccination histories could be confirmed 40 had received only inactivated polio vaccine (IPV) previously; of these 23% lacked antibody to at least one virus type, and they had less intestinal immunity to a challenge dose of OPV than those previously given OPV. Only two of the cadets known to have had OPV were non-immune - both had received a single dose following full courses of IPV. However, cadets who had received OPV had their last dose of vaccine more recently (average 4-6 years) than those who had received only IPV (all 12 years or more). The serum antibody response to a single booster dose of OPV, and the faecal excretion of each type of virus after vaccination, showed an inverse relation to the corresponding pre-vaccination antibody concentration. A single dose of OPV did not reliably boost the immunity of those who possessed adequate immunity, and a failure to respond was also observed in a proportion of the cadets with no detectable antibody, mostly in the case of type 3 antibody and particularly if antibody to types 1 or 2 virus was also absent. No evidence was obtained that intestinal immunity could be expected in the absence of detectable circulating antibody. The reasons for the absence of a serological response to OPV in some subjects are discussed and consideration is given to the practical significance of the findings. It is suggested that reinforcement of polio immunity at school-leaving is important, particularly at the present time when many of those aged 16-18 years will have been vaccinated only with IPV. A single dose of OPV is not ideal for this purpose, not only because a small proportion of persons are liable to be left unprotected, but also because failure to produce a reliable boost in persons with adequate immunity at the time of vaccination gives rise to the possibility that they may become susceptible later in adult life.
PMCID: PMC2129633  PMID: 177700
6.  Was there a disparity in age appropriate infant immunization uptake in the theatre of war in the North of Sri Lanka at the height of the hostilities?: a cross-sectional study in resettled areas in the Kilinochchi district 
It was long speculated that there could be under-immunized pockets in the war affected Northern part of Sri Lanka relative to other areas. With the cessation of hostilities following the military suppression of the rebellion, opportunities have arisen to appraise the immunization status of children in areas of re-settlement in former war ravaged districts.
We conducted a cross-sectional study to describe the coverage and age appropriateness of infant vaccinations in a former conflict district during the phase of re-settlement. The target population comprised all children of re-settled families in the age group of 12 – 23 months in the district. We selected a study sample of 300 children from among the target population using the WHO’s 30 cluster EPI survey method. Trained surveyors collected data using a structured checklist. The infant vaccination status was ascertained by reviewing vaccination records in the Child Health Development Record or any other alternative documentary evidence.
The survey revealed that the proportion of fully vaccinated children in the district was 91%. For individual vaccines, it ranged from 92% (measles) to 100% (BCG, DPT/OPV1). However, the age appropriateness of vaccination was less than 50% for all antigens except for BCG (94%). The maximum number of days of delay of vaccinations ranged from 21 days for BCG to 253 days for measles. Age appropriate vaccination rates significantly differed for DPT/OPV1-3 and measles during the conflict and post-conflict stages while it did not for the BCG. Age appropriate vaccination rates were significantly higher for DPT/OPV1-3 during the conflict while for the measles it was higher in the post conflict stage.
Though the vaccination coverage for infant vaccines in the war affected Kilinochchi district was similar to other districts in the country, it masked a disparity in terms of low age-appropriateness of infant immunizations given in field settings. This finding underscores the need for investigation of underlying reasons and introduction of remedial measures in the stage of restoring Primary Health Care services in the ex-conflict zone.
PMCID: PMC3534508  PMID: 23113899
Conflict; Vaccination; Coverage; Age-appropriate; Sri- Lanka
7.  Reasons for non-vaccination in pediatric patients visiting tertiary care centers in a polio-prone country 
Archives of Public Health  2013;71(1):19.
The Expanded Program on Immunization (EPI) was initiated by World Health Organization (WHO) in 1974 in order to save children from life threatening, disabling vaccine-preventable diseases (VPDs). In Pakistan, this program was launched in 1978 with the main objectives of eradicating polio by 2012, eliminating measles and neonatal tetanus by 2015, and minimizing the incidence of other VPDs. However, despite the efforts of government and WHO, this program has not received the amount of success that was desired. Hence, the objectives of this study were to elucidate the main reasons behind not achieving the full immunization coverage in Pakistan, the awareness of children’s attendant about the importance of vaccination, their attitudes, thoughts and fears regarding childhood immunization, and the major hurdles faced in pursuit of getting their children vaccinated.
This was an observational, cross-sectional, questionnaire-based study conducted during a one year period from 4th January, 2012 to 6th January, 2013 at the pediatric outpatient clinics of Civil Hospital (CHK) and National Institute of Child Health (NICH). We attempted to interview all the parents who could be approached during the period of the study. Thus, convenience sampling was employed. The parents were approached in the clinics and interviewed after seeking informed, written consent. Those patients who were not accompanied by either of their parents were excluded from the study. The study instrument comprised of three sections. The first section consisted was concerned with the demographics of the patient and the parents. The second section dealt with the reasons for complete vaccination or under-vaccination. The last section aimed to assess the knowledge, attitudes and beliefs of the respondents.
Out of 1044 patients, only 713(68.3%) were fully vaccinated, 239(22.9%) were partially vaccinated while 92(8.8%) had never been vaccinated. The vaccination status showed statistically significant association with ethnicity, income, residence, number of children and paternal occupation (p < 0.05 for all). The most common provocative factor for vaccination compliance was mass media (61.9%). The most common primary reason for non-vaccination was lack of knowledge (18.1%), whereas the most common secondary reason for non-vaccination was religious taboos (31.4%). Majority of the respondents demonstrated poor knowledge of EPI schedules or VPDs. However, most believed that there was a need for more active government/NGO involvement in this area.
The most common primary reason for non-vaccination, i.e. lack of knowledge, and the most common secondary reason, i.e. religious taboos, imply that there is dire need to promote awareness among the masses in collaboration with NGOs, and major religious and social organizations.
PMCID: PMC3716633  PMID: 23848348
8.  Surveillance of acute flaccid paralysis in Akwa Ibom State, Nigeria 2004–2009 
The last case of wild polio virus transmission occurred in Akwa Ibom state in October 2001; however, combination high routine immunization coverage with OPV, high quality AFP surveillance, mass immunization campaign in which two doses of potent oral polio vaccine is administered to eligible children and mop-up campaigns in areas with identified immunization or surveillance gaps has help the state in maintaining a free polio status for over ten years. This study was carried out to describe the characteristics of reported acute flaccid paralysis cases between 2004 and 2009, and to evaluate the performance of the acute flaccid paralysis surveillance system using indicators recommended by the World Health Organization.
A retrospective study was conducted among children, 0-15 years, by the World Health Organization (WHO) and Epidemiology unit of State Ministry of Health (SMOH), Uyo. The demographic characteristics and the results of isolation and identification of polio and other enteroviruses in stool samples sent to the WHO Polio Laboratory Ibadan for cases was analyzed.
A total of 521 cases of AFP (270 males and 251 females) aged 0 month to=15 years were reported by the surveillance system between 2004 and 2009. Those below 5 years of age accounted for 82.5% of cases reported and investigated. Of the 521 cases investigated 512 (98.3%) received at least three doses of oral polio vaccine, while 9(1.7) never received any oral polio vaccine (zero-dose). In all 5.1% of the isolates were Sabin, 7.9% non polio enterovirus (NPEV) and 2.3% were classified by national expert committee as compatible with poliomyelitis. There was consistent and steady increase in three critical indicators; Non polio AFP rate in children <15 years from 4.5 to 6.4 per 100 000 population, proportion of AFP cases with 2 stool specimens collected within 14 days of onset of paralysis from 57% in 2005 to 91% in 2009 and proportion of Local Government Areas (Districts) meeting both core indicators from 23% in 2005 to 87% in 2009. The highest numbers of cases were seen in the months of March, May and September.
This study showed high levels of surveillance performance with some challenges in reverse the cold chain system, the continuation and sustained AFP case detection, prompt investigation and response, improvement in the reserve cold chain system would achieve optimal standards recommended by WHO and might provide a good model for the eradication of poliomyelitis.
PMCID: PMC3215554  PMID: 22145065
Acute flaccid paralysis; Surveillance; Poliomyelitis; Nigeria
9.  Serological survey on immunity status against polioviruses in children and adolescents living in a border region, Apulia (Southern Italy) 
In 1988 the World Health Assembly adopted the goal to eradicate poliomyelitis by routine immunization using Oral Polio Vaccine (OPV). On 21 June 2002 the WHO European Region was declared polio-free. In 2008 poliomyelitis is still endemic in 4 countries (Nigeria, India, Pakistan, and Afghanistan), where 1201 new cases were registered in 2007; 107 sporadic cases were also notified in countries where poliovirus is not endemic. The aim of this work was to verify the level of antipoliomyelitis immunity status in children and adolescents in the Apulia region (south of Italy), which may be considered a border region due to its position.
704 blood specimens from a convenience sample were collected in six laboratories. The age of subjects enrolled was 0–15 years. The immunity against poliomyelitis was evaluated by neutralizing antibody titration in tissue culture microplates.
Seropositivity (neutralising antibodies titre ≥ 8) for polioviruses 1, 2 and 3 was detected in 100%, 99.8% and 99.4% of collected sera. Antibody titres were not lower in subjects who received either four doses of inactivated polio vaccine (IPV) or a sequential schedule consisting of two doses of IPV and two of oral polio vaccine than in subjects who received four doses of OPV.
These results confirmed current data of vaccine coverage for poliomyelitis: during the last ten years in Apulia, the coverage in 24 months old children was more than 90%. The high level of immunization found confirms the effectiveness both of the sequential schedule IPV-OPV and of the schedule all-IPV. Apulia region has to face daily arrivals of refugees and remains subject to the risk of the importation of poliovirus from endemic areas. Surveys aimed at determining anti-polio immunity in subpopulations as well as in the general population should be carried out.
PMCID: PMC2585574  PMID: 18973678
10.  Immunization Coverage: Role of Sociodemographic Variables 
Children are considered fully immunized if they receive one dose of BCG, three doses of DPT and polio vaccine each, and one measles vaccine. In India, only 44% of children aged 12–23 months are fully vaccinated and about 5% have not received any vaccination at all. Even if national immunization coverage levels are sufficiently high to block disease transmission, pockets of susceptibility may act as potential reservoirs of infection. This study was done to assess the immunization coverage in an urban slum area and determine various sociodemographic variables affecting the same. A total of 210 children were selected from study population using WHO's 30 cluster sampling method. Coverage of BCG was found to be the highest (97.1%) while that of measles was the lowest. The main reason for noncompliance was given as child's illness at the time of scheduled vaccination followed by lack of knowledge regarding importance of immunization. Low education status of mother, high birth order, and place of delivery were found to be positively associated with low vaccination coverage. Regular IEC activities (group talks, role plays, posters, pamphlets, and competitions) should be conducted in the community to ensure that immunization will become a “felt need” of the mothers in the community.
PMCID: PMC3872377  PMID: 24386572
11.  Support for children identified with acute flaccid paralysis under the global polio eradication programme in Uttar Pradesh, India: a qualitative study 
BMC Public Health  2012;12:229.
Cases of polio in India declined after the implementation of the polio eradication programme especially in these recent years. The programme includes surveillance of acute flaccid paralysis (AFP) to detect and diagnose cases of polio at early stage. Under this surveillance, over 40,000 cases of AFP are reported annually since 2007 regardless of the number of actual polio cases. Yet, not much is known about these children. We conducted a qualitative research to explore care and support for children with AFP after their diagnosis.
The research was conducted in a district of western Uttar Pradesh classified as high-risk area for polio. In-depth interviews with parents of children with polio (17), with non-polio AFP (9), healthcare providers (40), and key informants from community including international and government officers, religious leaders, community leaders, journalists, and academics (21) were performed.
Minimal medicine and attention were provided at government hospitals. Therefore, most parents preferred private-practice doctors for their children with AFP. Many were visited at homes to have stool samples collected by authorities. Some were visited repetitively following the sample collection, but had difficulty in understanding the reasons for these visits that pertained no treatment. Financial burden was a common concern among all families. Many parents expressed resentment for their children's disease, notably have been affected despite receiving multiple doses of polio vaccine. Both parents and healthcare providers lacked information and knowledge, furthermore poverty minimised the access to available healthcare services. Medicines, education, and transportation means were identified as foremost needs for children with AFP and residual paralysis.
Despite the high number of children diagnosed with AFP as part of the global polio eradication programme, we found they were not provided with sufficient medical support following their diagnosis. Improvement in the quality and sufficiency of the healthcare system together with integration of AFP surveillance with other services in these underprivileged areas may serve as a key solution.
PMCID: PMC3331818  PMID: 22439606
Acute flaccid paralysis; AFP Surveillance; Healthcare; India; Poliomyelitis; Pulse Polio Programme; Residual paralysis
12.  Use of a Novel Real-Time PCR Assay To Detect Oral Polio Vaccine Shedding and Reversion in Stool and Sewage Samples after a Mexican National Immunization Day▿ 
Journal of Clinical Microbiology  2011;49(5):1777-1783.
During replication, oral polio vaccine (OPV) can revert to neurovirulence and cause paralytic poliomyelitis. In individual vaccinees, it can acquire specific revertant point mutations, leading to vaccine-associated paralytic poliomyelitis (VAPP). With longer replication, OPV can mutate into vaccine-derived poliovirus (VDPV), which causes poliomyelitis outbreaks similar to those caused by wild poliovirus. After wild poliovirus eradication, safely phasing out vaccination will likely require global use of inactivated polio vaccine (IPV) until cessation of OPV circulation. Mexico, where children receive routine IPV but where OPV is given biannually during national immunization days (NIDs), provides a natural setting to study the duration of OPV circulation in a population primarily vaccinated with IPV. We developed a real-time PCR assay to detect and distinguish revertant and nonrevertant OPV serotype 1 (OPV-1), OPV-2, and OPV-3 from RNA extracted directly from stool and sewage. Stool samples from 124 children and 8 1-liter sewage samples from Orizaba, Veracruz, Mexico, collected 6 to 13 weeks after a NID were analyzed. Revertant OPV-1 was found in stool at 7 and 9 weeks, and nonrevertant OPV-2 and OPV-3 were found in stool from two children 10 weeks after the NID. Revertant OPV-1 and nonrevertant OPV-2 and -3 were detected in sewage at 6 and 13 weeks after the NID. Our real-time PCR assay was able to detect small amounts of OPV in both stool and sewage and to distinguish nonrevertant and revertant serotypes and demonstrated that OPV continues to circulate at least 13 weeks after a NID in a Mexican population routinely immunized with IPV.
PMCID: PMC3122635  PMID: 21411577
13.  The effect of mass immunisation campaigns and new oral poliovirus vaccines on the incidence of poliomyelitis in Pakistan and Afghanistan, 2001–11: a retrospective analysis 
Lancet  2012;380(9840):491-498.
Pakistan and Afghanistan are two of the three remaining countries yet to interrupt wild-type poliovirus transmission. The increasing incidence of poliomyelitis in these countries during 2010–11 led the Executive Board of WHO in January, 2012, to declare polio eradication a “programmatic emergency for global public health”. We aimed to establish why incidence is rising in these countries despite programme innovations including the introduction of new vaccines.
We did a matched case-control analysis based on a database of 46 977 children aged 0–14 years with onset of acute flaccid paralysis between Jan 1, 2001, and Dec 31, 2011. The vaccination history of children with poliomyelitis was compared with that of children with acute flaccid paralysis due to other causes to estimate the clinical effectiveness of oral poliovirus vaccines (OPVs) in Afghanistan and Pakistan by conditional logistic regression. We estimated vaccine coverage and serotype-specific vaccine-induced population immunity in children aged 0–2 years and assessed their association with the incidence of poliomyelitis over time in seven regions of Afghanistan and Pakistan.
Between Jan 1, 2001, and Dec 31, 2011, there were 883 cases of serotype 1 poliomyelitis (710 in Pakistan and 173 in Afghanistan) and 272 cases of poliomyelitis serotype 3 (216 in Pakistan and 56 in Afghanistan). The estimated clinical effectiveness of a dose of trivalent OPV against serotype 1 poliomyelitis was 12·5% (95% CI 5·6–18·8) compared with 34·5% (16·1–48·9) for monovalent OPV (p=0·007) and 23·4% (10·4–34·6) for bivalent OPV (p=0·067). Bivalent OPV was non-inferior compared with monovalent OPV (p=0·21). Vaccination coverage decreased during 2006–11 in the Federally Administered Tribal Areas (FATA), Balochistan, and Khyber Pakhtunkhwa in Pakistan and in southern Afghanistan. Although partially mitigated by the use of more effective vaccines, these decreases in coverage resulted in lower vaccine-induced population immunity to poliovirus serotype 1 in FATA and Balochistan and associated increases in the incidence of poliomyelitis.
The effectiveness of bivalent OPV is comparable with monovalent OPV and can therefore be used in eradicating serotype 1 poliomyelitis whilst minimising the risks of serotype 3 outbreaks. However, decreases in vaccination coverage in parts of Pakistan and southern Afghanistan have severely limited the effect of this vaccine.
Poliovirus Research subcommittee of WHO, Royal Society, and Medical Research Council.
PMCID: PMC3418593  PMID: 22766207
14.  Characteristics of persons refusing oral polio vaccine during the immunization plus days – Sokoto, Nigeria 2011 
The Pan African Medical Journal  2014;18(Suppl 1):10.
Nigeria, the only African country endemic for wild poliovirus, adopted Immunization Plus Days (IPD) to eradicate polio. Refusal of oral polio vaccine (OPV) by heads of households is a significant challenge. In Sokoto state, we determined characteristics of heads of households refusing OPV during IPD in 2011.
To evaluate reasons for refusals, we conducted a case control study among heads ofhouseholds accepting or refusing OPV vaccine. Noncompliant households were defined as households refusing OPV vaccination in last three rounds of IPDs while compliant households were those accepting vaccination. Interviewers administered a questionnaire to the heads of households to obtain information on socio-demographics, media habits, and knowledge of IPD.
Of the 121 (60 cases and 61 controls) interviews, 88 (73%) were from Sokoto north. Noncompliant heads of households were more likely to lack tertiary education (OR = 3.7, 95% CI, 1.6 - 9.2), believe that OPV is not safe (OR = 22, 95% CI, 7.1 - 76), lack access to functional radio (OR = 4.4, 95% CI, 1.4 - 15) and television (OR = 9.4, 95% CI, (1.9 - 63) andget information about IPD from town announcers (OR = 3.9, 95% CI, 1.3 - 12).
We conclude that noncompliant heads of households compared to compliant heads of households had low level of education, lacked knowledge of immunization, and had negative attitude towards OPV. They get information about OPV from town announcers and lacked access to functional radio and television. We recommended training of town announcers in polio communication and use of key communication messages preceding every round of IPD.
PMCID: PMC4199787  PMID: 25328629
Immunization; OPV; Vaccine refusal; WPV; poliomyelitis; knowledge; attitude; noncompliance
15.  A Population-Based Evaluation of a Publicly Funded, School-Based HPV Vaccine Program in British Columbia, Canada: Parental Factors Associated with HPV Vaccine Receipt 
PLoS Medicine  2010;7(5):e1000270.
Analysis of a telephone survey by Gina Ogilvie and colleagues identifies the parental factors associated with HPV vaccine uptake in a school-based program in Canada.
Information on factors that influence parental decisions for actual human papillomavirus (HPV) vaccine receipt in publicly funded, school-based HPV vaccine programs for girls is limited. We report on the level of uptake of the first dose of the HPV vaccine, and determine parental factors associated with receipt of the HPV vaccine, in a publicly funded school-based HPV vaccine program in British Columbia, Canada.
Methods and Findings
All parents of girls enrolled in grade 6 during the academic year of September 2008–June 2009 in the province of British Columbia were eligible to participate. Eligible households identified through the provincial public health information system were randomly selected and those who consented completed a validated survey exploring factors associated with HPV vaccine uptake. Bivariate and multivariate analyses were conducted to calculate adjusted odds ratios to identify the factors that were associated with parents' decision to vaccinate their daughter(s) against HPV. 2,025 parents agreed to complete the survey, and 65.1% (95% confidence interval [CI] 63.1–67.1) of parents in the survey reported that their daughters received the first dose of the HPV vaccine. In the same school-based vaccine program, 88.4% (95% CI 87.1–89.7) consented to the hepatitis B vaccine, and 86.5% (95% CI 85.1–87.9) consented to the meningococcal C vaccine. The main reasons for having a daughter receive the HPV vaccine were the effectiveness of the vaccine (47.9%), advice from a physician (8.7%), and concerns about daughter's health (8.4%). The main reasons for not having a daughter receive the HPV vaccine were concerns about HPV vaccine safety (29.2%), preference to wait until the daughter is older (15.6%), and not enough information to make an informed decision (12.6%). In multivariate analysis, overall attitudes to vaccines, the impact of the HPV vaccine on sexual practices, and childhood vaccine history were predictive of parents having a daughter receive the HPV vaccine in a publicly funded school-based HPV vaccine program. By contrast, having a family with two parents, having three or more children, and having more education was associated with a decreased likelihood of having a daughter receive the HPV vaccine.
This study is, to our knowledge, one of the first population-based assessments of factors associated with HPV vaccine uptake in a publicly funded school-based program worldwide. Policy makers need to consider that even with the removal of financial and health care barriers, parents, who are key decision makers in the uptake of this vaccine, are still hesitant to have their daughters receive the HPV vaccine, and strategies to ensure optimal HPV vaccine uptake need to be employed.
Please see later in the article for the Editors' Summary
Editors' Summary
About 10% of cancers in women occur in the cervix, the structure that connects the womb to the vagina. Every year, globally, more than a quarter of a million women die because of cervical cancer, which only occurs after the cervix has been infected with a human papillomavirus (HPV) through sexual intercourse. There are many types of HPV, a virus that infects the skin and the mucosa (the moist membranes that line various parts of the body, including the cervix). Although most people become infected with HPV at some time in their life, most never know they are infected. However, some HPV types cause harmless warts on the skin or around the genital area and several—in particular, HPV 16 and HPV 18, so-called high-risk HPVs—can cause cervical cancer. HPV infections are usually cleared by the immune system, but about 10% of women infected with a high-risk HPV develop a long-term infection that puts them at risk of developing cervical cancer.
Why Was This Study Done?
Screening programs have greatly reduced cervical cancer deaths in developed countries in recent decades by detecting the cancer early when it can be treated; but it would be better to prevent cervical cancer ever developing. Because HPV is necessary for the development of cervical cancer, vaccination of girls against HPV infection before the onset of sexual activity might be one way to do this. Scientists recently developed a vaccine that prevents infection with HPV 16 and HPV 18 (and with two HPVs that cause genital warts) and that should, therefore, reduce the incidence of cervical cancer. Publicly funded HPV vaccination programs are now planned or underway in several countries; but before girls can receive the HPV vaccine, parental consent is usually needed, so it is important to know what influences parental decisions about HPV vaccination. In this study, the researchers undertake a telephone survey to determine the uptake of the HPV vaccine by 11-year-old girls (grade 6) in British Columbia, Canada, and to determine the parental factors associated with vaccine uptake; British Columbia started a voluntary school-based HPV vaccine program in September 2008.
What Did the Researchers Do and Find?
In early 2009, the researchers contacted randomly selected parents of girls enrolled in grade 6 during the 2008–2009 academic year and asked them to complete a telephone survey that explored factors associated with HPV vaccine uptake. 65.1% of the 2,025 parents who completed the survey had consented to their daughter receiving the first dose of HPV vaccine. By contrast, more than 85% of the parents had consented to hepatitis B and meningitis C vaccination of their daughters. Nearly half of the parents surveyed said their main reason for consenting to HPV vaccination was the effectiveness of the vaccine. Conversely, nearly a third of the parents said concern about the vaccine's safety was their main reason for not consenting to vaccination and one in eight said they had been given insufficient information to make an informed decision. In a statistical analysis of the survey data, the researchers found that a positive parental attitude towards vaccination, a parental belief that HPV vaccination had limited impact on sexual practices, and completed childhood vaccination increased the likelihood of a daughter receiving the HPV vaccine. Having a family with two parents or three or more children and having well-educated parents decreased the likelihood of a daughter receiving the vaccine.
What Do These Findings Mean?
These findings provide one of the first population-based assessments of the factors that affect HPV vaccine uptake in a setting where there are no financial or health care barriers to vaccination. By identifying the factors associated with parental reluctance to agree to HPV vaccination for their daughters, these findings should help public-health officials design strategies to ensure optimal HPV vaccine uptake, although further studies are needed to discover why, for example, parents with more education are less likely to agree to vaccination than parents with less education. Importantly, the findings of this study, which are likely to be generalizable to other high-income countries, indicate that there is a continued need to ensure that the public receives credible, clear information about both the benefits and long-term safety of HPV vaccination.
Additional Information
Please access these Web sites via the online version of this summary at
The US National Cancer Institute provides information about cervical cancer for patients and for health professionals, including information on HPV vaccines (in English and Spanish)
The US Centers for Disease Control and Prevention also has information about cervical cancer and about HPV
The UK National Health Service Choices website has pages on cervical cancer and on HPV vaccination
More information about cervical cancer and HPV vaccination is available from the Macmillan cancer charity
ImmunizeBC provides general information about vaccination and information about HPV vaccination in British Columbia
MedlinePlus provides links to additional resources about cervical cancer (in English and Spanish)
PMCID: PMC2864299  PMID: 20454567
16.  Are we doing enough? Evaluation of the Polio Eradication Initiative in a district of Pakistan's Punjab province: a LQAS study 
BMC Public Health  2010;10:60.
The success of the Global Polio Eradication Initiative was remarkable, but four countries - Afghanistan, Pakistan, India and Nigeria - never interrupted polio transmission. Pakistan reportedly achieved all milestones except interrupting virus transmission. The aim of the study was to establish valid and reliable estimate for: routine oral polio vaccine (OPV) coverage, logistics management and the quality of monitoring systems in health facilities, NIDs OPV coverage, the quality of NIDs service delivery in static centers and mobile teams, and to ultimately provide scientific evidence for tailoring future interventions.
A cross-sectional study using lot quality assessment sampling was conducted in the District Nankana Sahib of Pakistan's Punjab province. Twenty primary health centers and their catchment areas were selected randomly as 'lots'. The study involved the evaluation of 1080 children aged 12-23 months for routine OPV coverage, 20 health centers for logistics management and quality of monitoring systems, 420 households for NIDs OPV coverage, 20 static centers and 20 mobile teams for quality of NIDs service delivery. Study instruments were designed according to WHO guidelines.
Five out of twenty lots were rejected for unacceptably low routine immunization coverage. The validity of coverage was questionable to extent that all lots were rejected. Among the 54.1% who were able to present immunization cards, only 74.0% had valid immunization. Routine coverage was significantly associated with card availability and socioeconomic factors. The main reasons for routine immunization failure were absence of a vaccinator and unawareness of need for immunization. Health workers (96.9%) were a major source of information. All of the 20 lots were rejected for poor compliance in logistics management and quality of monitoring systems. Mean compliance score and compliance percentage for logistics management were 5.4 ± 2.0 (scale 0-9) and 59.4% while those for quality of monitoring systems were 3.3 ± 1.2 (scale 0-6) and 54.2%. The 15 out of 20 lots were rejected for unacceptably low NIDs coverage by finger-mark. All of the 20 lots were rejected for poor NIDs service delivery (mean compliance score = 11.7 ± 2.1 [scale 0-16]; compliance percentage = 72.8%).
Low coverage, both routine and during NIDs, and poor quality of logistics management, monitoring systems and NIDs service delivery were highlighted as major constraints in polio eradication and these should be considered in prioritizing future strategies.
PMCID: PMC2845105  PMID: 20144212
17.  Immunization history of children with inflammatory bowel disease 
Protection against vaccine-preventable diseases is important in children with inflammatory bowel disease (IBD) due to frequent immunosuppressive therapy use. The chronic relapsing nature and treatment regimen of IBD may necessitate modified timing of immunizations.
To evaluate the completeness of immunizations in children with IBD.
Immunization records of all children with IBD followed at the Alberta Children’s Hospital (Calgary, Alberta) were reviewed. For children with incomplete immunization according to the province of Alberta schedule, the reasons for such were clarified. Demographic data and age at diagnosis were also collected.
Immunization records were obtained from 145 (79%) children with IBD. Fifteen children had incomplete routine childhood immunizations, including two with no previous immunizations. The most common incomplete immunizations included hepatitis B (n=9), diphtheria, tetanus, acellular pertussis at 14 to 16 years of age (n=7), and diphtheria, tetanus, acellular pertussis, inactivated polio at four to six years of age (n=6). The reasons for incomplete immunization included use of immunosuppressive therapy at time of scheduled immunization; IBD-related symptoms at time of scheduled immunization; parental refusal; recent move from elsewhere with different immunization schedule; unawareness of routine immunization; and needle phobia.
Although the majority of children with IBD had complete childhood immunizations, suboptimal immunizations were present in 10%. With increasing use of immunosuppressive therapy in IBD, physicians caring for children with IBD must periodically evaluate immunization status and ensure the completeness of childhood immunizations.
PMCID: PMC3742478  PMID: 23616959
Immunization; Immunosuppressive agents; Inflammatory bowel diseases
18.  Polio Eradication–Lessons from the Past and Future Perspective 
Background: India has recently achieved the “Polio free status” by WHO with stringent efforts of the Health Ministry to control its spread. However, we should not forget the lessons learnt from the failure of National malaria eradication Programme and National Tuberculosis control Programme which creates a need to assess the probable barriers for the various National Health Programmes. The present article presents an overview of the Polio Eradication programme in India highlighting the lessons learnt from the past. Also, it evaluates the reality behind full participation of Pulse Polio Programme.
Materials and Methods: The study results of a cross-sectional survey conducted with an aim to assess the probable reasons and barriers behind non compliance of Pulse Polio Programme among parents of children (1-5 yr of age) of Modinagar area have also been discussed. The survey instrument was a structured, 10 item, closed ended questionnaire.
Statistical analysis used: Chi-square test was used to analyze the difference between proportions of individual responses for each question and multiple logistic regression was used to assess relation between socio demographic parameter and absence from Polio Ravivaar.
Results: The study reveals a surprising 68% attendance of Pulse Polio programme which is far behind the desired goal. Most of the parents who did not attend polio ravivaar considered that there was no need for the repetition of Polio vaccine (76.9%) followed by their fear that the vaccine might get contaminated during transportation (74.5%). A significant positive association was found between older age group of the eligible children (4-5 yr, O.R.1.52), female gender, illiterate parents, distance of more than one km from residence to vaccination and lack of source of information (O.R. 1.47).
Conclusion: Efforts should be done to investigate the probable reasons behind non compliance for various immunization programmes to analyse the current situation in detail and formulate appropriate programs for coming years so that the efforts so far don’t go in vain and we secure a healthy Polio free nation for our future generations.
PMCID: PMC4149146  PMID: 25177640
Immunization; India; Non compliance; Polio eradication; Pulse polio programme; Perceived barriers
19.  Determinants of routine immunization coverage in Bungudu, Zamfara State, Northern Nigeria, May 2010 
The Pan African Medical Journal  2014;18(Suppl 1):9.
Immunization is a cost-effective public health intervention to reduce morbidity and mortality associated with infectious diseases. The Nigeria Demographic and Health Survey of 2008 indicated that only 5.4% of children aged 12-23 months in Bungudu, Zamfara State were fully immunized. We conducted this study to identify the determinants of routine immunization coverage in this community.
We conducted a cross-sectional study. We sampled 450 children aged 12-23 months. We interviewed mothers of these children using structured questionnaire to collect data on socio-demographic characteristics, knowledge on immunization, vaccination status of children and reasons for non-vaccination. We defined a fully immunized child as a child who had received one dose of BCG, three doses of oral polio vaccine, three doses of Diptheria-Pertusis-Tetanus vaccine and one dose of measles vaccine by 12 months of age. We performed bivariate analysis and logistic regression using Epi-info software.
The mean age of mothers and children were 27 years (standard error (SE): 0.27 year) and 17 months (SE: 0.8 month) respectively. Seventy nine percent of mothers had no formal education while 84% did not possess satisfactory knowledge on immunization. Only 7.6% of children were fully immunized. Logistic regression showed that possessing satisfactory knowledge (Adjusted OR=18.4, 95% CI=3.6-94.7) and at least secondary education (Adjusted OR=3.6, 95% CI=1.2-10.6) were significantly correlated with full immunization.
The major determinants of immunization coverage were maternal knowledge and educational status. Raising the level of maternal knowledge and increasing maternal literacy level are essential to improve immunization coverage in this community.
PMCID: PMC4199341  PMID: 25328628
Immunization; routine immunization; routine immunization coverage; fully immunized child; Nigeria
20.  Evaluation of AFP surveillance indicators in polio-free Ghana, 2009–2013 
BMC Public Health  2014;14:687.
Ghana recorded the last case of indigenous wild poliovirus in 1999 but suffered two more outbreaks in 2003 and 2008. Following the World Health Organization (WHO) guidelines, transmission was interrupted through high routine immunisation coverage with live-attenuated oral polio vaccine (OPV), effective acute flaccid paralysis (AFP) surveillance and supplementary immunisation activities (SIA). This article describes the results of a five-year surveillance of AFP in polio-free Ghana, evaluate the surveillance indicators and identify areas that need improvement.
We investigated 1345 cases of AFP from children aged less than 15 years reported to the Disease Surveillance Department from January 2009 to December 2013. Data on demographic characteristics, vaccination history, clinical presentation and virological investigation on stool specimens collected during investigation were analysed.
Of the specimens analysed, 56% were from males and 76.3% were from children less than 5 years of age. Twenty-four percent of the children received up to 3 doses of OPV, 57% received at least 4 doses while the status of 19% was unknown. Core AFP surveillance indicators were partly met for non-polio AFP rate while the WHO target for stool adequacy and timeliness was exceeded over the period of study. All the cases were classified virologically, however no wild polio was found. Sixty-day follow-up was conducted for 56.3% of cases and 8.6% cases classified as compactible with polio.
Both laboratory and epidemiological surveillance for AFP were efficient and many WHO targets were met. However, due to the risk of poliovirus importation prior to global eradication, longterm surveillance is required to provide a high degree of confidence in prevention of poliovirus infection in Ghana. Thus, efforts should be made to strengthen regional performance and to follow–up on all AFP cases in order to establish proper diagnoses for the causes of the AFP leading to proper care.
PMCID: PMC4094438  PMID: 24996415
Surveillance; Indicators; AFP; Regional Reference Polio Laboratory; Ghana
21.  A study of the knowledge and attitude towards pulse polio immunization in semi urban areas of South India 
The government of India launched the pulse polio immunization (PPI) programme in 1995 with the aim of eradicating poliomyelitis by the end of 2000. Despite this, 733 children with polio were reported in 2009 alone. Therefore, there is a need to understand the reason underlying such high numbers of cases after so many years of programme implementation. This study was performed to assess the knowledge of the general population about poliomyelitis and PPI and their attitude and practice towards PPI.
This cross-sectional study was undertaken in two semi- urban areas of Mangalore city. Only houses in which children under five lived were included in the study. Data was collected by interviewing any adult member of the household using a pretested questionnaire.
The literacy rate of study participants was 99%. Only 35(10.9%) participants knew the correct mode of transmission of polio. More than one quarter of the study population were under the misconception that polio is a curable disease. The primary source of information about PPI in majority of participants was the television (n = 192; 60%). Two-hundred and eighty eight (90%) participants knew that the purpose of PPI was to eradicate polio. Only 128 (40%) participants knew that polio drops can be given to children with mild illnesses and an identical number of participants knew that hot food stuff should not be given for at least half an hour following vaccination administration. Misconceptions such as PPI causing vaccine overdose was identified among 7 (2.2%) participants, it is a substitute for routine immunization was believed among 30 (9.4%) participants and that oral polio vaccine prevents other diseases was seen among 76 (23.7%) participants. The educational status of the participants was significantly associated with their awareness level (χ2 =13.668, DF=6, P=0.033).
This study identified a few important misconceptions associated with polio and PPI which need to be addressed by large scale awareness campaigns in order to achieve polio eradication in the near future.
PMCID: PMC3562928  PMID: 23386884
Polio; PPI; Awareness; Mangalore
22.  Maternal education is associated with vaccination status of infants less than 6 months in Eastern Uganda: a cohort study 
BMC Pediatrics  2010;10:92.
Despite provision of free childhood vaccinations, less than half of all Ugandan infants are fully vaccinated. This study compares women with some secondary schooling to those with only primary schooling with regard to their infants' vaccination status.
A community-based prospective cohort study conducted between January 2006 and May 2008 in which 696 pregnant women were followed up to 24 weeks post partum. Information was collected on the mothers' education and vaccination status of the infants.
At 24 weeks, the following vaccinations had been received: bacille Calmette-Guérin (BCG): 92%; polio-1: 91%; Diphteria-Pertussis-Tetanus-Hepatitis B-Haemophilus Influenza b (DPT-HB-Hib) 3 and polio-3: 63%. About 51% of the infants were fully vaccinated (i.e., had received all the scheduled vaccinations: BCG, polio 0, polio 1, DPT-HB-Hib1, polio 2, DPT-HB-Hib 2, polio 3 and DPT-HB-Hib 3). Only 46% of the infants whose mothers' had 5-7 years of primary education had been fully vaccinated compared to 65% of the infants whose mothers' had some secondary education. Infants whose mothers had some secondary education were less likely to miss the DPT-HB-Hib-2 vaccine (RR: 0.5, 95% CI: 0.3, 0.8), Polio-2 (RR: 0.4, 95%CI: 0.3, 0.7), polio-3 (RR: 0.5, 95%CI: 0.4, 0.7) and DPT-HB-Hib-3 (RR: 0.5, 95%CI: 0.4, 0.7). Other factors showing some association with a reduced risk of missed vaccinations were delivery at a health facility (RR = 0.8; 95%CI: 0.7, 1.0) and use of a mosquito net (RR: 0.8; 95%CI: 0.7, 1.0).
Infants whose mothers had a secondary education were at least 50% less likely to miss scheduled vaccinations compared to those whose mothers only had primary education. Strategies for childhood vaccinations should specifically target women with low formal education.
PMCID: PMC3019133  PMID: 21159193
23.  Gender inequity and age-appropriate immunization coverage in India from 1992 to 2006 
A variety of studies have considered the affects of India's son preference on gender differences in child mortality, sex ratio at birth, and access to health services. Less research has focused on the affects of son preference on gender inequities in immunization coverage and how this may have varied with time, and across regions and with sibling compositions. We present a systematic examination of trends in immunization coverage in India, with a focus on inequities in coverage by gender, birth order, year of birth, and state.
We analyzed data from three consecutive rounds of the Indian National Family Health Survey undertaken between 1992 and 2006. All children below five years of age with complete immunization histories were included in the analysis. Age-appropriate immunization coverage was determined for the following antigens: bacille Calmette-Guérin (BCG), oral polio (OPV), diphtheria, pertussis (whooping cough) and tetanus (DPT), and measles.
Immunization coverage in India has increased since the early 1990s, but complete, age-appropriate coverage is still under 50% nationally. Girls were found to have significantly lower immunization coverage (p<0.001) than boys for BCG, DPT, and measles across all three surveys. By contrast, improved coverage of OPV suggests a narrowing of the gender differences in recent years. Girls with a surviving older sister were less likely to be immunized compared to boys, and a large proportion of all children were found to be immunized considerably later than recommended.
Gender inequities in immunization coverage are prevalent in India. The low immunization coverage, the late immunization trends and the gender differences in coverage identified in our study suggest that risks of child mortality, especially for girls at higher birth orders, need to be addressed both socially and programmatically.
Abstract in Hindi
See the full article online for a translation of this abstract in Hindi.
PMCID: PMC3226235  PMID: 19828061
24.  Oral Polio Vaccine Influences the Immune Response to BCG Vaccination. A Natural Experiment 
PLoS ONE  2010;5(5):e10328.
Oral polio vaccine (OPV) is recommended to be given at birth together with BCG vaccine. While we were conducting two trials including low-birth-weight (LBW) and normal-birth-weight (NBW) infants in Guinea-Bissau, OPV was not available during some periods and therefore some infants did not receive OPV at birth, but only BCG. We investigated the effect of OPV given simultaneously with BCG at birth on the immune response to BCG vaccine.
Methods and Findings
We compared the in vitro and the in vivo response to PPD in the infants who received OPV and BCG with that of infants who received BCG only. At age 6 weeks, the in vitro cytokine response to purified protein derivate (PPD) of M. Tuberculosis was reduced in LBW and NBW infants who had received OPV with BCG. In a pooled analysis receiving OPV with BCG at birth was associated with significantly lower IL-13 (p = 0.041) and IFN-γ (p = 0.004) and a tendency for lower IL-10 (p = 0.054) in response to PPD. Furthermore, OPV was associated with reduced in vivo response to PPD at age 2 months, the prevalence ratio (PR) of having a PPD reaction being 0.75 (0.58–0.98), p = 0.033, and with a tendency for reduced likelihood of having a BCG scar (0.95 (0.91–1.00), p = 0.057)). Among children with a scar, OPV was associated with reduced scar size, the regression coefficient being −0.24 (−0.43—0.05), p = 0.012.
This study is the first to address the consequences for the immune response to BCG of simultaneous administration with OPV. Worryingly, the results indicate that the common practice in low-income countries of administering OPV together with BCG at birth may down-regulate the response to BCG vaccine.
PMCID: PMC2873948  PMID: 20502641
25.  Real-time Polymerase Chain Reaction Analysis of Sewage Samples to Determine Oral Polio Vaccine Circulation Duration and Mutation After Mexican National Immunization Weeks 
Oral polio vaccine (OPV) can mutate and cause outbreaks of paralytic poliomyelitis with prolonged replication. After poliovirus eradication, global use of inactivated polio vaccine (IPV) may be needed until all OPV stops circulating. Mexico, where children receive routine IPV but where OPV is given only during biannual national immunization weeks (NIWs), provides a natural setting to study duration of OPV circulation in a community primarily vaccinated with IPV.
One-liter sewage samples from four separate arroyos (creeks) near Orizaba, Mexico, were collected monthly for 12 months. Concentrated sewage underwent RNA extraction, reverse transcription, and real-time polymerase chain reaction (PCR) to detect OPV serotypes 1, 2, and 3 and their variants containing the serotype-specific point mutation in the 5′ untranslated region associated with neurovirulence.
OPV was detected 3, 4, 5, and 7 months after the May 2010 NIW, but was not detected at 6 or 8 months. A second and third NIW occurred in February 2011 and May 2011, and OPV was detected in the sewage monthly after both of these NIW through July 2011 when collection stopped. The OPV detected was primarily serotype 2 and predominantly contained the point mutations in the 5′ untranslated region associated with increased neurovirulence.
OPV was detected in sewage as late as 7 months after an NIW in a Mexican community primarily vaccinated with IPV, but was not detected at 8 months, suggesting that OPV circulation may have ceased. These data suggest that in communities with high vaccination rates, 1 or 2 years of IPV administration after OPV cessation could be sufficient to prevent outbreaks of paralytic poliomyelitis from vaccine-derived strains.
PMCID: PMC3529100  PMID: 23667738
Polio; OPV; Mexico; Sewage; PCR

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