The Swiss Immunization Schedule recommends two doses of MMR and four doses of Di, Te, Per, Pol, and Hib vaccine for children before 2 years of age, with catch-up shots available during the school years.1
Comparison of the national immunization coverage among toddlers for measles for the two most recent survey periods revealed that coverage increased from 82% in 1999-–2003 to 87% at one dose and 71% at two doses in 2005–2007.10
The recurring measles outbreaks, together with more intense efforts by the SFOPH and the cantons, probably contributed to this rise. Despite the increase, measles-containing vaccine coverage is far from 95% for two doses, the level necessary to attain herd immunity to eliminate this disease.12
Our results show that for measles vaccination at one dose, only six cantons had coverage ≥90% for toddlers, and no canton had measles-containing vaccine coverage of ≥90% at two doses for schoolchildren.
An epidemiologic assessment of measles between 2006 and 2007 by Muscat et al. confirmed that Switzerland is among the top five countries responsible for 85% of the recorded measles cases in Europe, contributing 27% of the total cases in 2007 with the highest incidence rate of 78.8 and 58.2 per 100,000 inhabitants in children aged 5–9 and 10–14 years, respectively.13
Between November 2006 and September 2009, there were 4,415 reported cases of measles in Switzerland, resulting in an incidence rate of 58 per 100,000 inhabitants, with one canton supplying 24% of the total cases. In January 2009, a 12-year-old girl from France, who was hospitalized in Geneva, died from encephalitis due to measles infection.14
To reach the goal of measles elimination in the European region by 2010, efforts to achieve this goal were intensified. These efforts included aggressive vaccination information campaigns and media exposure, participation in the European vaccination week, strengthened measles surveillance, commitment from the Chief Medical -Officers to achieve coverage ≥95%, and political support from Parliament with consideration for introducing compulsory measles immunization, as required in the U.S. at school entry.15–17
Based on the World Health Organization (WHO) guidelines to control outbreaks of vaccine-preventable childhood diseases, the SFOPH defined operational goals for coverage levels for the Swiss National Immunization Program as follows: coverage ≥95% nationally and ≥90% in each canton at three doses of Di, Te, Per, and Pol vaccines for toddlers, at four doses for children aged 5–7 years, and at five doses for those aged 16 years.18
For the most part, the reported coverage estimates at the national and canton level for Di, Te, and Pol for 2- and 8-year-olds have reached this goal, but those for the 16-year-olds are still too low. Of particular concern is the low coverage rate for Per for schoolchildren, despite the change from -whole-cell to acellular vaccine and the recommendation of a fourth and fifth dose in 1996 in the Swiss Immunization Schedule.
Raising Per catch-up vaccination in this age group should be a priority, as adolescents and especially adults have long been recognized as a source of Bordetella pertussis transmission in young, unprotected infants, in addition to the problems of waning immunity over time and vaccine efficacy lower than the desired coverage needed for herd immunity.19–22
As with measles, because of the suboptimal coverage level, circulation of the pathogen is unavoidable and can have tragic consequences, as in the case of the 2-year-old in one canton who died from a Per infection in 2009, the first mortality case in 10 years.23
Although not presented in this article, there was a general increase in coverage at the canton level, with only two cantons exhibiting a possible decrease for all eight targeted antigens for toddlers; one canton for 8-year-olds for all except Per and Hib vaccines; and one canton for teenagers for Di, Te, and Pol vaccines. The decrease could have been due to use of complementary and alternative medicine (e.g., homeopathy), a change in the school vaccination program, and/or a change in the survey methodology. Studies, including the last survey in 1999–2003, have shown the negative influence of complementary and alternative medicine on vaccination coverage and the potential impact of schools on vaccination programs.10,24–28
Race/ethnicity and nationality are also highly correlated with measles coverage, which has also been observed in many other studies.29–33
Unlike these studies, our results showed that children in the two younger age groups whose nationality was not Swiss were better vaccinated against measles than Swiss children. Research by Mixer et al. confirmed that awareness of the controversy surrounding MMR vaccination was higher among white mothers whose toddlers had lower MMR coverage, as compared with mothers of other racial/ethnic minority groups whose children had higher MMR coverage.34
There was no difference for 16-year-olds, as we see that logistic problems and access to health service may be barriers to being fully immunized. Furthermore, many of these children of foreign background do not have their vaccination records from their native country, although some have said that they were fully vaccinated before coming to Switzerland. Without any written records, we had to assume that these vaccinations were not administered. This problem is similar to record scattering, as documentations are incomplete due to multiple health-care providers, resulting in a negative impact on vaccination coverage.35,36
Record scattering increases the risk of losing immunization records and hinders the evaluation and improvements of vaccination coverage.
The highest immunization coverage estimates were found most often in the Latin-speaking region. With the most recent measles epidemic, evidence shows that measles incidence is inversely proportional to vaccination coverage, with the lowest incidence in the Latin-speaking region.4
Furthermore, vaccination for Di is mandatory in three Latin-speaking cantons (one canton only until 2008), which could have also influenced the higher immunization coverage among these regions. The difference in immunization rates for compulsory and facultative vaccinations has been established in other studies.37–39
While the French-speaking cantons appeared to have higher coverage than the German-speaking ones for the two younger age groups, this impact was not observed for adolescents. Rather, immunization coverage for teenagers appears to be influenced more by school vaccination programs, which are confounded by the fact that all French-speaking cantons have school vaccination programs, unlike in the German- and Italian-speaking regions where it varies by canton; this association was also observed in the first survey.10
Furthermore, alternative immunization plans adopted by complementary and alternative medicine practitioners recommend MMR vaccination for children to be delayed until 10–14 years of age, and only if protection has not yet been acquired through natural infection.40,41
In-depth multivariate analyses are currently being executed to examine the impact of some of these important factors.
The coverage estimates obtained were based on the number of doses administered, which could be an overestimation, as has been shown in studies analyzing coverage by validity of vaccination doses and/or age-appropriate vaccination.42–46
Overestimation and vaccinations not timely administered will leave some children unprotected. As mentioned previously, coverage estimates could also be an underestimation, as vaccinations not documented in the submitted immunization cards were not taken into consideration. Recall bias was eliminated, as only data documented in the vaccination cards or provided by the primary care physicians or school health nurses were included in the analysis.
Although participation was quite high at 80%–85%, more effort is still needed to increase response level, as our study and other published literature have shown it to be associated with coverage.47,48
Our survey used a mix-mode data collection method (via mailings and telephone), which has been observed to produce less biased results with limited cost.49,50
However, due to greater volume of solicitation for participation in surveys and for commercial purposes, resistance to these contacts has risen, with more families blocking publication of their numbers in telephone books and at the municipality level.
In addition to increasing participation at the children's level, participation from cantons and municipalities must also be consistently maintained. Between 2005 and 2007, only one canton declined to participate; currently, data are being collected for the SNVCS for 2008–2010, with participation uncertain for three cantons. Although participation by municipalities was high at 97.3% between 2005 and 2007, reservations to release requested information have increased, with the minimum in one canton in the current cycle at an unacceptable 80%. Furthermore, coverage estimates ascertained from a three-year study cycle may be less sensitive to detecting changes in national coverage levels. More support at the political level for the SNVCS is required.
Finally, the participants in our survey were significantly different from the census data and the nonrespondents. Although statistical adjustments were made, including poststratification, they may not have been enough to account for nonresponse bias and the different sampling methodology. However, from our study, only 0.3% of nonrespondents who gave a reason for not participating fundamentally opposed vaccination.