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1.  Vaccination coverage for seasonal influenza among residents and health care workers in Norwegian nursing homes during the 2012/13 season, a cross-sectional study 
BMC Public Health  2014;14:434.
Background
WHO has set a goal of 75% vaccination coverage (VC) for seasonal influenza for residents and also recommends immunization for all healthcare workers (HCWs) in nursing homes (NHs). We conducted a cross-sectional study to estimate the VC for seasonal influenza vaccination in Norwegian NHs in 2012/2013 since the VC in NHs and HCWs is unknown.
Methods
We gathered information from NHs concerning VC for residents and HCWs, and vaccination costs for HCWs, using a web-based questionnaire. We calculated VC among NH residents by dividing the number of residents vaccinated by the total number of residents for each NH. VC among HCWs was similarly calculated by dividing the number of HCWs vaccinated by the total number of HCWs for each NH. The association between VC and possible demographic variables were explored.
Results
Of 910 NHs, 354 (38.9%) responded. Median VC per NH was 71.7% (range 0-100) among residents and 0% (range 0-100) among HCWs, with 214 (60%) NHs reporting that none of their HCWs was vaccinated. Median VC for HCWs in NHs with an annual vaccination campaign was 0% (range 0-53), compared to when they did not have an annual vaccination campaign 0% (range 0-12); the distributions in the two groups differed significantly (Mann–Whitney U, P = 0.006 two tailed).
Conclusion
Median influenza VC in Norwegian NHs was marginally lower than recommended among residents and exceptionally low among HCWs. The VC in HCWs was significantly higher when NHs had an annual vaccination campaign. We recommend that NHs implement measures to increase VC among residents and HCWs, including vaccination campaigns and studies to identify potential barriers to vaccination.
doi:10.1186/1471-2458-14-434
PMCID: PMC4049507  PMID: 24885662
2.  Influenza and hepatitis B vaccination coverage among healthcare workers in Croatian hospitals: a series of cross-sectional surveys, 2006–2011 
BMC Infectious Diseases  2013;13:520.
Background
Healthcare workers (HCWs) are at an increased risk of exposure to and transmission of infectious diseases. Vaccination lowers morbidity and mortality of HCWs and their patients. To assess vaccination coverage for influenza and hepatitis B virus (HBV) among HCWs in Croatian hospitals, we conducted yearly nationwide surveys.
Methods
From 2006 to 2011, all 66 Croatian public hospitals, representing 43–60% of all the HCWs in Croatia, were included. Statistical analysis was performed using the Kruskal–Wallis analysis of variance, Dunn’s multiple comparison analysis and the chi-square test, as appropriate.
Results
The median seasonal influenza vaccination coverage rates in pre-pandemic (2006–2008) seasons were 36%, 25% and 29%, respectively. By occupation, influenza vaccination rates among physicians were 33 ± 21%, 33 ± 22% among graduate nurses, 30±34% among other HCWs, 26 ± 21% among housekeeping and the lowest, 23 ± 17%, among practical nurses (p < 0.01). In 2009–2010 season, seasonal influenza vaccination coverage was 30%, while overall vaccination coverage against pandemic influenza was fewer than 5%. Median vaccination coverage in the post-pandemic seasons of 2010–2011 and 2011–2012 decreased to 15% and 14%, respectively (reduction of 24% and 35%, respectively, p < 0.0001). Meanwhile, the median mandatory HBV vaccination coverage was 98%, albeit with considerable differences according to work setting (range 19–100%) and occupation (range 4–100%).
Conclusions
We found substantial year-on-year variations in seasonal influenza vaccination rates, with reduction in post pandemic influenza seasons. HBV vaccination is satisfactory compared to seasonal influenza vaccination coverage, although substantial variations by occupation and work setting were observed. These findings highlight the need for national strategies that optimize vaccination coverage among HCWs in Croatian hospitals. Further studies are needed to establish the potential role of mandatory vaccination for seasonal influenza.
doi:10.1186/1471-2334-13-520
PMCID: PMC3840606  PMID: 24192278
Influenza; Hepatitis B; Healthcare workers; Vaccination
3.  Personal Decision-Making Criteria Related to Seasonal and Pandemic A(H1N1) Influenza-Vaccination Acceptance among French Healthcare Workers 
PLoS ONE  2012;7(7):e38646.
Background
Influenza-vaccination rates among healthcare workers (HCW) remain low worldwide, even during the 2009 A(H1N1) pandemic. In France, this vaccination is free but administered on a voluntary basis. We investigated the factors influencing HCW influenza vaccination.
Methods
In June–July 2010, HCW from wards of five French hospitals completed a cross-sectional survey. A multifaceted campaign aimed at improving vaccination coverage in this hospital group was conducted before and during the 2009 pandemic. Using an anonymous self-administered questionnaire, we assessed the relationships between seasonal (SIV) and pandemic (PIV) influenza vaccinations, and sociodemographic and professional characteristics, previous and current vaccination statuses, and 33 statements investigating 10 sociocognitive domains. The sociocognitive domains describing HCWs' SIV and PIV profiles were analyzed using the classification-and-regression–tree method.
Results
Of the HCWs responding to our survey, 1480 were paramedical and 401 were medical with 2009 vaccination rates of 30% and 58% for SIV and 21% and 71% for PIV, respectively (p<0.0001 for both SIV and PIV vaccinations). Older age, prior SIV, working in emergency departments or intensive care units, being a medical HCW and the hospital they worked in were associated with both vaccinations; while work shift was associated only with PIV. Sociocognitive domains associated with both vaccinations were self-perception of benefits and health motivation for all HCW. For medical HCW, being a role model was an additional domain associated with SIV and PIV.
Conclusions
Both vaccination rates remained low. Vaccination mainly depended on self-determined factors and for medical HCW, being a role model.
doi:10.1371/journal.pone.0038646
PMCID: PMC3407215  PMID: 22848342
4.  Determinants of influenza vaccination uptake among Italian healthcare workers 
We analyzed seasonal influenza vaccination coverage among the Italian healthcare workers (HCW) in order to identify socio-demographic and clinical determinants of vaccination.
We used data from the survey “Health and health care use in Italy,” which comprised interviews of 5,336 HCWs For each respondent, information on socioeconomic, health conditions, self-perceived health and smoking status were obtained. After bivariate analysis, we used multilevel regression models to assess determinants of immunization. Overall 20.8% of HCWs (95%CI 19.7–21.9) reported being vaccinated against seasonal influenza.
After controlling for potential confounders, multilevel regression revealed that older workers have a higher likelihood of vaccine uptake (OR = 6.07; 95% CI 4.72–7.79). Conversely, higher education was associated with lower vaccine uptake (OR = 0.65; 95% IC 0.50–0.83). Those suffering from diabetes (OR = 2.07; 95% CI 1.19–1.69), COPD (OR = 1.95; 95% CI 1.31–2.89) and cardiovascular diseases (OR = 1.48 95% CI 1.11–1.96) were more likely to be vaccinated. Likewise, smokers, or former smokers receive more frequently the vaccination (OR = 1.40; 95% CI 1.15–1.70; OR = 1.54; 95% CI 1.24–1.91, respectively) compared with never-smokers as well as those HCWs reporting fair or poor perceived health status (ORs of 1.68, 95% CI 1.30–2.18).
Vaccine coverage among HCWs in Italy remains low, especially among those with no comorbidities and being younger than 44 y old. This behavior not only raises questions regarding healthcare organization, infection control in healthcare settings and clinical costs, but also brings up ethical issues concerning physicians who seem not to be very concerned about the impact of the flu on themselves, as well as on their patients. Influenza vaccination campaigns will only be effective if HCWs understand their role in influenza transmission and prevention, and realize the importance of vaccination as a preventive measure
doi:10.4161/hv.22997
PMCID: PMC3903913  PMID: 24064543
administration and dosage; attitude of health personnel; health behavior; human prevention and control; influenza; influenza vaccines; socioeconomic factors
5.  Healthcare workers as parents: attitudes toward vaccinating their children against pandemic influenza A/H1N1 
BMC Public Health  2010;10:596.
Background
Both the health care workers (HCWs) and children are target groups for pandemic influenza vaccination. The coverage of the target populations is an important determinant for impact of mass vaccination. The objective of this study is to determine the attitudes of HCWs as parents, toward vaccinating their children with pandemic influenza A/H1N1 vaccine.
Methods
A cross-sectional questionnaire survey was conducted with health care workers (HCWs) in a public hospital during December 2009 in Istanbul. All persons employed in the hospital with or without a health-care occupation are accepted as HCW. The HCWs who are parents of children 6 months to 18 years of age were included in the study. Pearson's chi-square test and logistic regression analysis was applied for the statistical analyses.
Results
A total of 389 HCWs who were parents of children aged 6 months-18 years participated study. Among all participants 27.0% (n = 105) reported that themselves had been vaccinated against pandemic influenza A/H1N1. Two third (66.1%) of the parents answered that they will not vaccinate their children, 21.1% already vaccinated and 12.9% were still undecided. Concern about side effect was most reported reason among who had been not vaccinated their children and among undecided parents. The second reason for refusing the pandemic vaccine was concerns efficacy of the vaccine. Media was the only source of information about pandemic influenza in nearly one third of HCWs. Agreement with vaccine safety, self receipt of pandemic influenza A/H1N1 vaccine, and trust in Ministry of Health were found to be associated with the positive attitude toward vaccinating their children against pandemic influenza A/H1N1.
Conclusions
Persuading parents to accept a new vaccine seems not be easy even if they are HCWs. In order to overcome the barriers among HCWs related to pandemic vaccines, determination of their misinformation, attitudes and behaviors regarding the pandemic influenza vaccination is necessary. Efforts for orienting the HCWs to use evidence based scientific sources, rather than the media for information should be considered by the authorities.
doi:10.1186/1471-2458-10-596
PMCID: PMC3091558  PMID: 20932342
6.  A Time Off Incentive Was Not Associated with Influenza Vaccination Acceptance among Healthcare Workers 
Objectives. The national influenza vaccination rate among healthcare workers (HCWs) remains low despite clear benefits to patients, coworkers, and families. We sought to evaluate formally the effect of a one-hour time off incentive on attitudes towards influenza vaccination during the 2011-2012 influenza season. Methods. All HCWs at the Philadelphia Veterans Affairs (VA) Medical Center were invited to complete an anonymous web-based survey. We described respondents' characteristics and attitudes toward influenza vaccination and determined the relationship of specific attitudes with respondents' acceptance of influenza vaccination, using a 5-point Likert scale. Results. We analyzed survey responses from 154 HCWs employed at the Philadelphia VA Medical Center, with a response rate of 8%. Among 121 respondents who reported receiving influenza vaccination, 34 (28%, 95% CI 20–37%) reported agreement with the statement that the time off incentive made a difference in their decision to accept influenza vaccination. Conclusions. Our study provides evidence that modest incentives such as one-hour paid time off will be unlikely to promote influenza vaccination rates within medical facilities. More potent interventions that include mandatory vaccination combined with penalties for noncompliance will likely provide the only means to achieve near-universal influenza vaccination among HCWs.
doi:10.1155/2013/209491
PMCID: PMC3710596  PMID: 23878733
7.  Protecting patients, protecting healthcare workers: a review of the role of influenza vaccination 
International Nursing Review  2011;59(2):161-167.
MUSIC T. (2012) A review of the role the role of influenza vaccination in protecting patients, protecting healthcare workers the role of influenza vaccination. International Nursing Review59, 161–167
Aim:
Many health authorities recommend routine influenza vaccination for healthcare workers (HCWs), and during the 2009 A (H1N1) pandemic, the World Health Organization (WHO) recommended immunization of all HCWs worldwide. As this remains an important area of policy debate, this paper examines the case for vaccination, the role of local guidelines, barriers to immunization and initiatives to increase uptake.
Background:
Seasonal influenza is a major threat to public health, causing up to 1 million deaths annually. Extensive evidence supports the vaccination of priority groups, including HCWs. Immunization protects HCWs themselves, and their vulnerable patients from nosocomial influenza infections. In addition, influenza can disrupt health services and impact healthcare organizations financially. Immunization can reduce staff absences, offer cost savings and provide economic benefits.
Methods:
This paper reviews official immunization recommendations and HCW vaccination studies, including a recent International Federation of Pharmaceutical Manufacturers and Associations (IFPMA) survey of 26 countries from each region of the world.
Results:
HCW immunization is widely recommended and supported by the WHO. In the IFPMA study, 88% of countries recommended HCW vaccination, and 61% supported this financially (with no correlation to country development status). Overall, coverage can be improved, and research shows that uptake may be impacted by lack of conveniently available vaccines and misconceptions regarding vaccine safety/efficacy and influenza risk.
Conclusions:
Many countries recommend HCW vaccination against influenza. In recent years, there has been an increased uptake rate among HCWs in some countries, but not in others. Several initiatives can increase coverage, including education, easy access to free vaccines and the use of formal declination forms. The case for HCW vaccination is clear, and in an effort to further accelerate uptake as a patient safety measure, an increasing number of healthcare organizations, particularly in the USA, are implementing mandatory immunization policies, similar to other obligatory hygiene measures. However, it would be desirable if similar high vaccination uptake rates could be achieved through voluntary procedures.
doi:10.1111/j.1466-7657.2011.00961.x
PMCID: PMC3418836  PMID: 22591085
Coverage; Education; Guideline; Influenza; Policy; Recommendation; Reimbursement; Seasonal; Vaccine
8.  Influenza vaccination among healthcare workers in a multidisciplinary University hospital in Italy 
BMC Public Health  2008;8:422.
Background
Annual influenza vaccination is recommended for healthcare workers (HCWs) in order to reduce the morbidity associated with influenza in healthcare settings. The aim of this study was to evaluate the current vaccination status of the HCWs in one of Italy's largest multidisciplinary University Hospitals.
Methods
Between February 1 and March 31, 2006, we carried out a cross-sectional study of influenza vaccination coverage among HCWs at the University Hospital Fondazione IRCCS "Ospedale Maggiore Policlinico, Mangiagalli e Regina Elena", Milan, Italy. After receiving a brief description of the aim of the study, 2,143 (95%: 1,064 physicians; 855 nurses; 224 paramedics) of 2,240 HCWs self-completed an anonymous questionnaire.
Results
Influenza vaccination coverage was very low in all specialties, varying from 17.6% in the Emergency Department to 24.3% in the Surgery Department, and knowledge of influenza epidemiology and prevention was poor. The factors positively associated with being vaccinated were an age of ≥ 45 years, considering influenza a potentially severe disease, and being aware of the high-risk categories for which influenza vaccination is strongly recommended; those that negatively associated with being vaccinated were being female, working in the Medicine Department, and being a nurse or paramedic.
Conclusion
Despite strong recommendations, influenza vaccination coverage seemed to be very low among HCWs of all specialties, with differences between areas and types of employment. Specific continuous educational and vaccination programs for different targets should be urgently organized to reduce morbidity and mortality in high-risk patients, contain nosocomial outbreaks, and ensure an appropriate socioeconomic impact.
doi:10.1186/1471-2458-8-422
PMCID: PMC2651144  PMID: 19105838
9.  BRIEF REPORT: Influenza Vaccination and Health Care Workers in the United States 
OBJECTIVE
To determine influenza vaccination rates among U.S. health care workers (HCWs) by demographic and occupational categories.
DESIGN AND PARTICIPANTS
We analyzed data from the 2000 National Health Interview Survey (NHIS). Weighted multivariable analyses were used to evaluate the association between HCW occupation and other variables potentially related to receipt of influenza vaccination. HCWs were categorized based on standard occupational classifications as health-diagnosing professions, health-assessing professions, health aides, health technicians; or health administrators.
MAIN INDEPENDENT VARIABLES
Demographic characteristics and occupation category.
MAIN OUTCOME VARIABLES
Receipt of influenza vaccination within 12 months of survey.
ANALYSIS
Descriptive statistics and weighted multivariable logistic regression.
RESULTS
There were 1,651 HCWs in the final sample. The overall influenza vaccination rate for HCWs was 38%. After weighted multivariable analyses, HCWs who were under 50 (odds ratio [OR] 0.67%, 95% confidence interval [CI]: 0.50 to 0.89, compared with HCWs 50 to 64), black (OR 0.57 95% CI: 0.42, 0.78, compared with white HCWs), or were health aides (OR 0.73%, 95% CI: 0.51, 1.04, compared with health care administrators and administrative support staff) had lower odds of having been vaccinated against influenza.
CONCLUSIONS
The overall influenza vaccination rate among HCWs in the United States is low. Workers who are under 50, black, or health aides have the lowest rates of vaccinations. Interventions seeking to improve HCW vaccination rates may need to target these specific subgroups.
doi:10.1111/j.1525-1497.2006.00325.x
PMCID: PMC1484661  PMID: 16606378
Influenza vaccinations; health care workers; National Health Interview Survey; nosocomial infection; employee health
10.  Planning and process evaluation of a multi-faceted influenza vaccination implementation strategy for health care workers in acute health care settings 
BMC Infectious Diseases  2013;13:235.
Background
Influenza transmitted by health care workers (HCWs) is a potential threat to frail patients in acute health care settings. Therefore, immunizing HCWs against influenza should receive high priority. Despite recommendations of the World Health Organization, vaccine coverage of HCWs remains low in all European countries. This study explores the use of intervention strategies and methods to improve influenza vaccination rates among HCWs in an acute care setting.
Methods
The Intervention Mapping (IM) method was used to systematically develop and implement an intervention strategy aimed at changing influenza vaccination behaviour among HCWs in Dutch University Medical Centres (UMCs). Carried out during the influenza seasons 2009/2010 and 2010/2011, the interventions were then qualitatively and quantitatively evaluated by way of feedback from participating UMCs and the completion of a web-based staff questionnaire in the following spring of each season.
Results
The IM method resulted in the development of a transparent influenza vaccination intervention implementation strategy. The intervention strategy was offered to six Dutch UMCs in a randomized in a clustered Randomized Controlled Trial (RCT), where three UMCs were chosen for intervention, and three UMCs acted as controls. A further two UMCs elected to have the intervention. The qualitative process evaluation showed that HCWs at four of the five intervention UMCs were responsive to the majority of the 11 relevant behavioural determinants resulting from the needs assessment in their intervention strategy compared with only one of three control UMCs. The quantitative evaluation among a sample of HCWs revealed that of all the developed communication materials, HCWs reported the posters as the most noticeable.
Conclusions
Our study demonstrates that it is possible to develop a structured implementation strategy for increasing the rate of influenza vaccination by HCWs in acute health care settings. The evaluation also showed that it is impossible to expose all HCWs to all intervention methods (which would have been the best case scenario). Further study is needed to (1) improve HCW exposure to intervention methods; (2) determine the effect of such interventions on vaccine uptake among HCWs; and (3) assess the impact on clinical outcomes among patients when such interventions are enacted.
doi:10.1186/1471-2334-13-235
PMCID: PMC3680164  PMID: 23701921
Influenza vaccination; Health care workers; Intervention mapping; Intervention implementation; Acute health care
11.  How to develop a program to increase influenza vaccine uptake among workers in health care settings? 
Background
Apart from direct protection and reduced productivity loss during epidemics, the main reason to immunize healthcare workers (HCWs) against influenza is to provide indirect protection of frail patients through reduced transmission in healthcare settings. Because the vaccine uptake among HCWs remains far below the health objectives, systematic programs are needed to take full advantage of such vaccination. In an earlier report, we showed a mean 9% increase of vaccine uptake among HCWs in nursing homes that implemented a systematic program compared with control homes, with higher rates in those homes that implemented more program elements. Here, we report in detail the process of the development of the implementation program to enable researchers and practitioners to develop intervention programs tailored to their setting.
Methods
We applied the intervention mapping (IM) method to develop a theory- and evidence-based intervention program to change vaccination behaviour among HCWs in nursing homes.
Results
After a comprehensive needs assessment, we were able to specify proximal program objectives and selected methods and strategies for inducing behavioural change. By consensus, we decided on planning of three main program components, i.e., an outreach visit to all nursing homes, plenary information meetings, and the appointment of a program coordinator -- preferably a physician -- in each home. Finally, we planned program adoption, implementation, and evaluation.
Conclusion
The IM methodology resulted in a systematic, comprehensive, and transparent procedure of program development. A potentially effective intervention program to change influenza vaccination behaviour among HCWs was developed, and its impact was assessed in a clustered randomised controlled trial.
doi:10.1186/1748-5908-6-47
PMCID: PMC3115899  PMID: 21595877
12.  Barriers to pandemic influenza vaccination and uptake of seasonal influenza vaccine in the post-pandemic season in Germany 
BMC Public Health  2012;12:938.
Background
In Germany, annual vaccination against seasonal influenza is recommended for certain target groups (e.g. persons aged ≥60 years, chronically ill persons, healthcare workers (HCW)). In season 2009/10, vaccination against pandemic influenza A(H1N1)pdm09, which was controversially discussed in the public, was recommended for the whole population. The objectives of this study were to assess vaccination coverage for seasonal (seasons 2008/09-2010/11) and pandemic influenza (season 2009/10), to identify predictors of and barriers to pandemic vaccine uptake and whether the controversial discussions on pandemic vaccination has had a negative impact on seasonal influenza vaccine uptake in Germany.
Methods
We analysed data from the ‘German Health Update’ (GEDA10) telephone survey (n=22,050) and a smaller GEDA10-follow-up survey (n=2,493), which were both representative of the general population aged ≥18 years living in Germany.
Results
Overall only 8.8% of the adult population in Germany received a vaccination against pandemic influenza. High socioeconomic status, having received a seasonal influenza shot in the previous season, and belonging to a target group for seasonal influenza vaccination were independently associated with the uptake of pandemic vaccines. The main reasons for not receiving a pandemic vaccination were ‘fear of side effects’ and the opinion that ‘vaccination was not necessary’. Seasonal influenza vaccine uptake in the pre-pandemic season 2008/09 was 52.8% among persons aged ≥60 years; 30.5% among HCW, and 43.3% among chronically ill persons. A decrease in vaccination coverage was observed across all target groups in the first post-pandemic season 2010/11 (50.6%, 25.8%, and 41.0% vaccination coverage, respectively).
Conclusions
Seasonal influenza vaccination coverage in Germany remains in all target groups below 75%, which is a declared goal of the European Union. Our results suggest that controversial public discussions about safety and the benefits of pandemic influenza vaccination may have contributed to both a very low uptake of pandemic vaccines and a decreased uptake of seasonal influenza vaccines in the first post-pandemic season. In the upcoming years, the uptake of seasonal influenza vaccines should be carefully monitored in all target groups to identify if this trend continues and to guide public health authorities in developing more effective vaccination and communication strategies for seasonal influenza vaccination.
doi:10.1186/1471-2458-12-938
PMCID: PMC3527143  PMID: 23113995
Vaccination; Influenza; Coverage; Pandemic; Germany
13.  Vaccination Behaviour Influences Self-Report of Influenza Vaccination Status: A Cross-Sectional Study among Health Care Workers 
PLoS ONE  2012;7(7):e39496.
Background
Published influenza vaccination coverage in health care workers (HCW) are calculated using two sources: self-report and vaccination records. The objective of this study was to determine whether self-report is a good proxy for recorded vaccination in HCW, as the degree of the relationship is not known, and whether vaccine behaviour influences self-reporting.
Methods
A cross-sectional study was conducted using a self-administered survey during September 2010. Considering the vaccination record as the gold standard of vaccination, the properties of self-report as a proxy of the record (sensitivity, specificity, positive predictive value, negative predictive value) were calculated. Concordance between the vaccination campaigns studied (2007–2010) was made using the Kappa index, and discordance was analyzed using McNemar’s test.
Results
248 HCW responded. The 95% confidence intervals of coverage according to the vaccination record and to self-report overlapped, except for 2007, and the Kappa index showed a substantial concordance, except for 2007. McNemar’s test suggested that differences between discordant cases were not due to chance and it was found that the proportion of unvaccinated discordant cases was higher than that of vaccinated discordant cases.
Conclusions
In our study population, self-reported influenza vaccination coverage in HCW in the previous two years is a good proxy of the vaccination record. However, vaccination behaviour influences the self-report and explains a trend to overestimate coverage in self-reporting compared to the vaccination record. The sources of coverage should be taken into account whenever comparisons are made.
doi:10.1371/journal.pone.0039496
PMCID: PMC3394773  PMID: 22808039
14.  The Effects of Influenza Vaccination of Health Care Workers in Nursing Homes: Insights from a Mathematical Model 
PLoS Medicine  2008;5(10):e200.
Background
Annual influenza vaccination of institutional health care workers (HCWs) is advised in most Western countries, but adherence to this recommendation is generally low. Although protective effects of this intervention for nursing home patients have been demonstrated in some clinical trials, the exact relationship between increased vaccine uptake among HCWs and protection of patients remains unknown owing to variations between study designs, settings, intensity of influenza seasons, and failure to control all effect modifiers. Therefore, we use a mathematical model to estimate the effects of HCW vaccination in different scenarios and to identify a herd immunity threshold in a nursing home department.
Methods and Findings
We use a stochastic individual-based model with discrete time intervals to simulate influenza virus transmission in a 30-bed long-term care nursing home department. We simulate different levels of HCW vaccine uptake and study the effect on influenza virus attack rates among patients for different institutional and seasonal scenarios. Our model reveals a robust linear relationship between the number of HCWs vaccinated and the expected number of influenza virus infections among patients. In a realistic scenario, approximately 60% of influenza virus infections among patients can be prevented when the HCW vaccination rate increases from 0 to 1. A threshold for herd immunity is not detected. Due to stochastic variations, the differences in patient attack rates between departments are high and large outbreaks can occur for every level of HCW vaccine uptake.
Conclusions
The absence of herd immunity in nursing homes implies that vaccination of every additional HCW protects an additional fraction of patients. Because of large stochastic variations, results of small-sized clinical trials on the effects of HCW vaccination should be interpreted with great care. Moreover, the large variations in attack rates should be taken into account when designing future studies.
Using a mathematical model to simulate influenza transmission in nursing homes, Carline van den Dool and colleagues find that each additional staff member vaccinated further reduces the risk to patients.
Editors' Summary
Background.
Every winter, millions of people catch influenza, a contagious viral disease of the nose, throat, and airways. Most people recover completely from influenza within a week or two but some develop life-threatening complications such as bacterial pneumonia. As a result, influenza outbreaks kill about half a million people—mainly infants, elderly people, and chronically ill individuals—each year. To minimize influenza-related deaths, the World Health Organization recommends that vulnerable people be vaccinated against influenza every autumn. Annual vaccination is necessary because flu viruses continually make small changes to the viral proteins (antigens) that the immune system recognizes. This means that an immune response produced one year provides only partial protection against influenza the next year. To provide maximum protection against influenza, each year's vaccine contains disabled versions of the major circulating strains of influenza viruses.
Why Was This Study Done?
Most Western countries also recommend annual flu vaccination for health care workers (HCWs) in hospitals and other institutions to reduce the transmission of influenza to vulnerable patients. However, many HCWs don't get a regular flu shot, so should efforts be made to increase their rate of vaccine uptake? To answer this question, public-health experts need to know more about the relationship between vaccine uptake among HCWs and patient protection. In particular, they need to know whether a high rate of vaccine uptake by HCWs will provide “herd immunity.” Herd immunity occurs because, when a sufficient fraction of a population is immune to a disease that passes from person to person, infected people rarely come into contact with susceptible people, which means that both vaccinated and unvaccinated people are protected from the disease. In this study, the researchers develop a mathematical model to investigate the relationship between vaccine uptake among HCWs and patient protection in a nursing home department.
What Did the Researchers Do and Find?
To predict influenza virus attack rates (the number of patient infections divided by the number of patients in a nursing home department during an influenza season) at different levels of HCW vaccine uptake, the researchers develop a stochastic transmission model to simulate epidemics on a computer. This model predicts that as the HCW vaccination rate increases from 0 (no HCWs vaccinated) to 1 (all the HCWs vaccinated), the expected average influenza virus attack rate decreases at a constant rate. In the researchers' baseline scenario—a nursing home department with 30 beds where patients come into contact with other patients, HCWs, and visitors—the model predicts that about 60% of the patients who would have been infected if no HCWs had been vaccinated are protected when all the HCWs are vaccinated, and that seven HCWs would have to be vaccinated to protect one patient. This last figure does not change with increasing vaccine uptake, which indicates that there is no level of HCW vaccination that completely stops the spread of influenza among the patients; that is, there is no herd immunity. Finally, the researchers show that large influenza outbreaks can happen by chance at every level of HCW vaccine uptake.
What Do These Findings Mean?
As with all mathematical models, the accuracy of these predictions may depend on the specific assumptions built into the model. Therefore the researchers verified that their findings hold for a wide range of plausible assumptions. These findings have two important practical implications. First, the direct relationship between HCW vaccination and patient protection and the lack of any herd immunity suggest that any increase in HCW vaccine uptake will be beneficial to patients in nursing homes. That is, increasing the HCW vaccination rate from 80% to 90% is likely to be as important as increasing it from 10% to 20%. Second, even 100% HCW vaccination cannot guarantee that influenza outbreaks will not occasionally occur in nursing homes. Because of the large variation in attack rates, the results of small clinical trials on the effects of HCW vaccination may be inaccurate and future studies will need to be very large if they are to provide reliable estimates of the amount of protection that HCW vaccination provides to vulnerable patients.
Additional Information.
Please access these Web sites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.0050200.
Read the related PLoSMedicine Perspective by Cécile Viboud and Mark Miller
A related PLoSMedicine Research Article by Jeffrey Kwong and colleagues is also available
The World Health Organization provides information on influenza and on influenza vaccines (in several languages)
The US Centers for Disease Control and Prevention provide information for patients and professionals on all aspects of influenza (in English and Spanish)
The UK Health Protection Agency also provides information on influenza
MedlinePlus provides a list of links to other information about influenza (in English and Spanish)
The UK National Health Service provides information about herd immunity, including a simple explanatory animation
The European Centre for Disease Prevention and Control provides an overview on the types of influenza
doi:10.1371/journal.pmed.0050200
PMCID: PMC2573905  PMID: 18959470
15.  How complete is influenza immunization coverage? A study in 75 nursing and residential homes for elderly people. 
BACKGROUND. Elderly people in residential accommodation are particularly susceptible to outbreaks of influenza. Up to 70% of residents can become ill and many will develop complications or die. Immunization can prevent such outbreaks and is cost-effective. AIM. A study was undertaken to measure influenza immunization coverage in residential accommodation for elderly people and to identify factors that might influence uptake. METHOD. In March 1992, a questionnaire survey was conducted of all 113 registered nursing and residential homes for elderly people, in South Glamorgan. It asked about the demographic characteristics of people resident on 1 October 1991, their influenza immunization history and the homes' arrangements for administering immunizations. RESULTS. Questionnaires were returned by respondents from 75 homes (66%). Mean influenza vaccine uptake was 67%. Uptake was higher in nursing homes (mean of 82% in eight nursing homes) than in homes registered as both nursing and residential homes (mean of 76% in six homes) or in residential homes (mean of 65% in 61 homes). Nearly all of those immunized (94%) had been immunized by the end of November 1991. Residents who were reported to have underlying disease that increased their risk of complications if they contracted influenza were no more likely to have been immunized than those without risk factors. Immunization coverage varied considerably both between homes and between general practices. Most general practices in South Glamorgan had several elderly people in residential accommodation on their list, but only nine out of 64 practices had immunized all the elderly residents on their list and 12 practices had immunized fewer than half. Routine recording of immunization status in nursing and residential homes was variable, often as a consequence of poor communication between the primary health care team and staff at the home. Even where recorded, retrieval of the data was sometimes a problem. CONCLUSION. Influenza immunization coverage could be improved if general practices held a case register of all at-risk patients including elderly residents, and if nursing and residential homes were encouraged to keep better immunization records. These measures would facilitate year-on-year monitoring of influenza immunization coverage and the targeting of homes with low immunization coverage.
PMCID: PMC1239336  PMID: 7576847
16.  Long-Term Persistence of Seroprotection by Hepatitis B Vaccination in Healthcare Workers of Southern Italy 
Hepatitis Monthly  2012;12(9):e6025.
Background
The impact of hepatitis B virus (HBV) vaccination campaigns on HBV epidemiology needs to be evaluated, in order to assess the long-term immunity offered by vaccines against HBV.
Objectives
To evaluate the current status of anti-HBV vaccine coverage among healthcare workers (HCWs) in Southern Italy, and to determine the long-term persistence of antibodies to hepatitis B surface antigens (anti-HBs) in such a cohort of subjects.
Patients and Methods
A longitudinal, retrospective seroepidemiological survey was conducted among 451 HCWs, who were working at or visiting, the Occupational Health Department of a city hospital, in Catania, Italy, between January 1976 and December 2010.
Results
At the 30-year follow-up (mean follow-up 10.15 ± 5.96 years, range 0.74-30), 261 HCWs had detectable anti-HBs titers indicating a persistence of seroprotection of 89.4% (out of 292 anti-HBs positive results, three months after vaccination). An inadequate vaccination schedule was the strongest predictor of antibody loss during follow-up (OR = 8.37 95% CI: 5.41-12.95, P < 0.001). A Kaplan-Maier survival curve revealed that the persistence of anti-HBs 30 years after vaccination, was 92.2% for high responders, while it was only 27.3% for low responders (P = 0.001).
Conclusions
A good level of seroprotection persisted in 57.9% of the subjects after 30 years. Factors related to this immunization status confirmed the importance of vaccinating HCWs early in their careers and ensuring an adequate vaccination schedule. However, with particular reference to the low rate of hepatitis B vaccine coverage among HCWs in Southern Italy, the implementation of a new educational intervention as part of an active vaccination program is needed.
doi:10.5812/hepatmon.6025
PMCID: PMC3475028  PMID: 23087756
Hepatitis B Virus; Vaccines; Health Personnel; Vaccination
17.  Impact of the 2004-2005 Influenza Vaccine Shortage on Immunization Practices in Long-Term Care Facilities 
Objective
To assess the response of long-term care facilities (LTCFs) to the 2004-2005 influenza vaccine shortage and the impact on resident and healthcare worker (HCW) immunization rates.
Methods
A 12-item questionnaire was sent to 824 randomly selected LTCFs in December 2004. The following 2 open-ended questions were also asked: “How did you cope with the vaccine shortage?” and “Who helped you get your supply?” Immunization rates reported by LTCF administrators for 2003-2003 and 2003-2004 were compared with those for 2004-2005. Immunization rates were defined as the proportion of all eligible residents and HCWs who received influenza vaccine.
Results
Responses were received from 380 LTCFs (46.3%), which had a total of 38,447 beds. Resident mean influenza immunization rates (±SD) decreased from 85% ± 15.3% in 2002-2003 and 85.1% ± 15.3% in 2003-2004 to 81.9% ± 19.4% in the 2004-2005 influenza season (P = .025). The immunization rates among HCWs also decreased from 51% in 2002-2003 and 2003-2004 to 38.4% in 2004-2005 (P < .001). In response to one of the open-ended questions, 96 facilities (25.3%) reported that they obtained vaccine from 2 or more sources. Eight percent commented on specific intensified infection control efforts, and only 2.3% commented on emergency preparedness.
Conclusions
The influenza vaccine shortage in 2004-2005 impacted immunization practices of LTCFs across the United States, leading to decreases in both resident and HCW vaccination rates. The significant decrease in vaccination rates in LTCFs is of concern and has broad implications for policy makers working on emergency preparedness for a possible pandemic of influenza.
doi:10.1086/503179
PMCID: PMC3319392  PMID: 16622817
18.  Acceptance of a Vaccine Against Novel Influenza A (H1N1) Virus Among Health Care Workers in Two Major Cities in Mexico 
Archives of medical research  2009;40(8):705-711.
Background and Aims
Further cases of novel influenza A (H1N1) outbreak are expected in the coming months. Vaccination has been proven to be essential to control a pandemic of influenza; therefore, considerable efforts and resources have been devoted to develop a vaccine against the influenza A (H1N1) virus. With the current availability of the vaccine, it will be important to immunize as many people as possible. However, previous data with seasonal influenza vaccines have shown that there are multiple barriers related to perceptions and attitudes of the population that influence vaccine use. The aim of the study was to evaluate the acceptance of a newly developed vaccine against pandemic (H1N1) 2009 influenza A among healthcare workers (HCW) in Mexico.
Methods
We conducted a cross-sectional study among HCW in three hospitals in the two largest cities in Mexico—Mexico City and Guadalajara—between June and September 2009.
Results
A total of 1097 HCW participated in the survey. Overall, 80% (n = 880) intended to accept the H1N1 pandemic vaccine and 71.6% (n = 786) reported they would recommend the vaccine to their patients. Doctors were more likely to accept and recommend the vaccine than nurses. HCWs who intend to be immunized will be more likely to do so if they know that the vaccine is safe and effective.
Conclusions
Knowledge of the willingness to accept the vaccine can be used to plan strategies that will effectively respond to the needs of the population studied, reducing the health and economic impact of novel influenza A (H1N1) virus.
doi:10.1016/j.arcmed.2010.01.004
PMCID: PMC2854164  PMID: 20304260
Vaccine acceptance; Influenza A (H1N1) virus; Health care workers
19.  INFLUENZA VACCINATION IN HEALTHCARE WORKERS: 10-YEAR EXPERIENCE OF A LARGE HEALTHCARE ORGANIZATION 
Objective
To describe the results of different measures implemented to improve compliance with the healthcare worker (HCW) influenza immunization program at BJC HealthCare between 1997 and 2007.
Design
Descriptive retrospective study.
Setting
BJC HealthCare, a 13-hospital nonprofit healthcare organization in the Midwest.
Methods
Review and analysis of HCW influenza vaccination data from all BJC HealthCare Occupational Health Services and hospitals between 1997 and 2007. Occupational health staff, infection prevention personnel and key influenza vaccine campaign leaders were also interviewed regarding implementation measures during the study years.
Results
At the end of 2007, BJC HealthCare had approximately 26,000 employees. Using multiple progressive interventions, influenza vaccination rates among BJC employees increased from 45% in 1997 to 71.9% in 2007 (p<0.001). The influenza vaccination rate in 2007 was significantly higher than in 2006, 71.9% versus 54.2% (p<0.001). Five hospitals had influenza vaccination rates over the target goal of 80% in 2007. The most successful interventions were adding influenza vaccination rates to the incented quality scorecard and declination statements, both implemented in 2007. The most important barriers identified in the interviews related to HCWs’ misconceptions about influenza vaccination and a perceived lack of leadership support.
Conclusions
Influenza vaccination rates in HCWs significantly improved with multiple interventions over the years. However, the BJC HealthCare influenza vaccination target of 80% was not attained at all hospitals with these measures. More aggressive interventions such as implementing mandatory influenza vaccination policies are needed to achieve higher vaccination rates.
doi:10.1086/650449
PMCID: PMC3919446  PMID: 20055666
20.  The impact of prophylaxis of healthcare workers on influenza pandemic burden 
Several models have rationalized the use of antiviral drugs as an early control measure for delaying the progression and limiting the size of outbreaks during an influenza pandemic. However, the strategy for use of these drugs is still under debate. We evaluated the impact of prophylaxis of healthcare workers (HCWs) through a mathematical model that considers attack rates in a range of 25–35% in the general population and 25–50% among HCWs. Simulations and uncertainty analysis using the demographics of the province of Ontario, Canada show that increasing prophylaxis coverage of HCWs has little impact on reducing the reproduction number of disease transmission and may not prevent the occurrence of an outbreak if expected. However, it does enable a high level of treatment, which substantially reduces morbidity and mortality in the population as a whole. Therefore, prophylaxis of HCWs should be considered an important part of public health efforts for minimizing influenza pandemic burden and its socio-economic disruption.
doi:10.1098/rsif.2006.0204
PMCID: PMC2373383  PMID: 17360253
influenza pandemic; antivirals; prophylactic treatment; epidemic models
21.  Knowledge, attitudes and anxiety towards influenza A/H1N1 vaccination of healthcare workers in Turkey 
BMC Infectious Diseases  2010;10:281.
Background
This study aimed to analyze the factors associated with knowledge and attitudes about influenza A (H1N1) and vaccination, and possible relations of these factors with anxiety among healthcare workers (HCW).
Methods
The study used a cross-sectional descriptive design, and it was carried out between 23 November and 4 December 2009. A total of 300 HCW from two hospitals completed a questionnaire. Data collection tools comprised a questionnaire and the State-Trait Anxiety Inventory (STAI).
Results
Vaccination rate for 2009 pandemic influenza A(H1N1) among HCW was low (12.7%). Most of the respondents believed the vaccine was not safe and protective. Vaccination refusal was mostly related to the vaccine's side effects, disbelief to vaccine's protectiveness, negative news about the vaccine and the perceived negative attitude of the Prime Minister to the vaccine. State anxiety was found to be high in respondents who felt the vaccine was unsafe.
Conclusions
HCW considered the seriousness of the outbreak, their vaccination rate was low. In vaccination campaigns, governments have to aim at providing trust, and media campaigns should be used to reinforce this trust as well. Accurate reporting by the media of the safety and efficacy of influenza vaccines and the importance of vaccines for the public health would likely have a positive influence on vaccine uptake. Uncertain or negative reporting about the vaccine is detrimental to vaccination efforts.
doi:10.1186/1471-2334-10-281
PMCID: PMC3161359  PMID: 20863386
22.  Sustained Low Influenza Vaccination Rates in US Healthcare Workers 
Preventive medicine  2010;50(4):210-212.
INTRODUCTION
A substantial morbidity and mortality burden attributable to the influenza virus is observed annually in the United States. Healthcare workers are an occupational group at increased risk of exposure, demonstrated to transmit influenza to their patient populations, and vital to the care of these patient populations. The prevention of the spread of the flu is a significant public health concern. In the present study, we examined influenza vaccination rates and their 5-year trends within the major occupational healthcare worker groups and compared them to non-Healthcare Workers.
METHODS
Using data from the nationally representative 2004–2008 National Health Interview Survey (NHIS), US healthcare workers (n=6,394) were analyzed.
RESULTS
Seasonal influenza vaccination coverage estimates remain substantially low among all healthcare workers, highest among the health diagnosing and treating practitioners (52.3%), and lowest among other healthcare support occupations (32.0%). Among all other occupational groups, pooled influenza vaccination rates were highest for white collar workers (24.7%), and lowest for farm workers (11.7%). There were no significant upward or downward trends in influenza vaccination rates for any healthcare or other occupational worker group during the five-year survey period.
CONCLUSION
Improving these low vaccination rates among healthcare workers warrants a comprehensive national approach to influenza prevention that includes education and strong encouragement of routine annual vaccination among healthcare workers. Policy enhancements such as free provision of seasonal influenza vaccine, coverage for treatment and workers compensation for vaccine-related complications are needed.
doi:10.1016/j.ypmed.2010.01.001
PMCID: PMC2839028  PMID: 20079761
Flu; Vaccination; healthcare workers; occupation; epidemiology
23.  A Surveillance System to Reduce Transmission of Pandemic H1N1 (2009) Influenza in a 2600-Bed Medical Center 
PLoS ONE  2012;7(3):e32731.
Background
Concerns have been raised about how the transmission of emerging infectious diseases from patients to healthcare workers (HCWs) and vice versa could be recognized and prevented in a timely manner. An effective strategy to block transmission of pandemic H1N1 (2009) influenza in HCWs is important.
Methodology/Principal Findings
An infection control program was implemented to survey and prevent nosocomial outbreaks of H1N1 (2009) influenza at a 2,600-bed, tertiary-care academic hospital. In total, 4,963 employees at Kaohsiung Chang Gung Memorial Hospital recorded their temperature and received online education on control practices for influenza infections. Administration records provided vaccination records and occupational characteristics of all HCWs. Early recognition of a pandemic H1N1 (2009) influenza case was followed by a semi-structured questionnaire to analyze possible routes of patient contact, household contact, or unspecified contact. Surveillance spanned August 1, 2009 to January 31, 2010; 51 HCWs were confirmed to have novel H1N1 (2009) influenza by quantitative real-time reverse transcription polymerase chain reaction. Prevalence of patient contact, household contact, or unspecified contact infection was 13.7% (7/51), 13.7% (7/51), and 72.5% (37/51), respectively. The prevalence of the novel H1N1 infection was significantly lower among vaccinated HCWs than among unvaccinated HCWs (p<0.001). Higher viral loads in throat swabs were found in HCWs with patient and household contact infection than in those with unspecified contact infection (4.15 vs. 3.53 copies/mL, log10, p = 0.035).
Conclusion
A surveillance system with daily temperature recordings and online education for HCWs is important for a low attack rate of H1N1 (2009) influenza transmission before H1N1 (2009) influenza vaccination is available, and the attack rate is further decreased after mass vaccination. Unspecified contact infection rates were significantly higher than that of patient contact and household contact infection, highlighting the need for public education of influenza transmission in addition to hospital infection control.
doi:10.1371/journal.pone.0032731
PMCID: PMC3302803  PMID: 22427871
24.  Knowledge of Evidence-Based Urinary Catheter Care Practice Recommendations Among Healthcare Workers in Nursing Homes 
Objectives
This study assessed the knowledge of recommended urinary catheter care practices among nursing home (NH) healthcare workers (HCWs) in Southeast Michigan.
Design
A self-administered survey.
Setting
Seven nursing homes in Southeast Michigan.
Participants
Three hundred and fifty-six healthcare workers.
Methods
An anonymous, self-administered survey of HCWs (nurses & nurse aides) in seven NHs in 2006. The survey included questions about respondent characteristics and knowledge about indications, care, and personal hygiene pertaining to urinary catheters. The association of knowledge measures with occupation (nurses vs. aides) was assessed using generalized estimating equations.
Results
A total of 356 of 440 HCWs (81%) responded. Over 90% of HCWs were aware of measures such as cleaning around the catheter daily, glove use, and hand hygiene with catheter manipulation. They were less aware of research-proven recommendations of not disconnecting the catheter from its bag (59% nurses vs. 30% aides, P < .001), not routinely irrigating the catheter (48% nurses vs. 8% aides, P < .001), and hand hygiene even after casual contact (60% nurses vs. 69% aides, P = .07). HCWs were also unaware of recommendations regarding alcohol-based handrub (27% nurses & 32% aides with correct responses, P = .38). HCWs reported sources, both informal (such as nurse supervisors) and formal (in-services), of knowledge about catheter care.
Conclusion
Wide discrepancies remain between research-proven recommendations pertaining to urinary catheter care and HCWs' knowledge. Nurses and aides differ in their knowledge of recommendations against harmful practices, such as disconnecting the catheter from the bag and routinely irrigating catheters. Further research should focus on strategies to enhance dissemination of proven infection control practices in NHs.
doi:10.1111/j.1532-5415.2010.02964.x
PMCID: PMC2955179  PMID: 20662957
urinary catheter; nursing homes; translating research into practice
25.  Long-Term Immunogenicity of the Pandemic Influenza A/H1N1 2009 Vaccine among Health Care Workers: Influence of Prior Seasonal Influenza Vaccination 
Health care workers (HCWs) are at great risk of influenza infection and transmission. Vaccination for seasonal influenza is routinely recommended, but this strategy should be reconsidered in a pandemic situation. Between October 2009 and September 2010, a multicenter study was conducted to assess the long-term immunogenicity of the A/H1N1 2009 monovalent influenza vaccine among HCWs compared to non-health care workers (NHCWs). The influence of prior seasonal influenza vaccination was also assessed with respect to the immunogenicity of pandemic H1N1 influenza vaccine. Serum hemagglutinin inhibition titers were determined prevaccination and then at 1, 6, and 10 months after vaccination. Of the 360 enrolled HCW subjects, 289 participated in the study up to 10 months after H1N1 monovalent influenza vaccination, while 60 of 65 NHCW subjects were followed up. Seroprotection rates, seroconversion rates, and geometric mean titer (GMT) ratios fulfilled the European Union's licensure criteria for influenza A/California/7/2009 (H1N1) at 1 month after vaccination in both the HCWs and NHCWs, without any significant difference. At 6 months after vaccination, the seroprotection rate was more significantly lowered among the NHCWs than among the HCWs (P < 0.01). Overall, postvaccination (1, 6, and 10 months after vaccination) GMTs for A/California/7/2009 (H1N1) were significantly lower among the seasonal influenza vaccine recipients than among the nonrecipients (P < 0.05). In conclusion, HCWs should be encouraged to receive an annual influenza vaccination, considering the risk of repeated exposure. However, prior reception of seasonal influenza vaccine showed a negative influence on immunogenicity for the pandemic A/H1N1 2009 influenza vaccine.
doi:10.1128/CVI.00725-12
PMCID: PMC3623406  PMID: 23365206

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