Routine vaccination against pertussis and the risk of childhood asthma: a population-based cohort study

BACKGROUND: In industrialized countries vaccination coverage remains suboptimal, partly because of perception of an increased risk of asthma. Epidemiologic studies of the association between childhood vaccinations and asthma have provided conflicting results, possibly for methodologic reasons such as unreliable vaccination data, biased reporting, and reverse causation. A recent review stressed the need for additional, adequately controlled large-scale studies. OBJECTIVE: Our goal was to determine if routine childhood vaccination against pertussis was associated with subsequent development of childhood wheezing disorders and asthma in a large population-based cohort study. METHODS: In 6811 children from the general population born between 1993 and 1997 in Leicestershire, United Kingdom, respiratory symptom data from repeated questionnaire surveys up to 2003 were linked to independently collected vaccination data from the National Health Service database. We compared incident wheeze and asthma between children of different vaccination status (complete, partial, and no vaccination against pertussis) by computing hazard ratios. Analyses were based on 6048 children, 23 201 person-years of follow-up, and 2426 cases of new-onset wheeze. RESULTS: There was no evidence for an increased risk of wheeze or asthma in children vaccinated against pertussis compared with nonvaccinated children. Adjusted hazard ratios comparing fully and partially vaccinated with nonvaccinated children were close to one for both incident wheeze and asthma. CONCLUSION: This study provides no evidence of an association between vaccination against pertussis in infancy and an increased risk of later wheeze or asthma and does not support claims that vaccination against pertussis might significantly increase the risk of childhood asthma.

Economic evaluation of varicella vaccination in Swiss children and adolescents

This study explores the effects of three different 2-dose varicella zoster virus (VZV) vaccination strategies in Switzerland. The EVITA model was used to assess clinical benefits and costs of strategies (1) vaccination of 11-15 year old adolescents with a negative or uncertain history for chickenpox, (2) universal vaccination of toddlers at age 1 to 2 years, and (3) strategy 2 plus catch-up vaccination of 11-15 year old susceptible adolescents. The cost-effectiveness analysis compares strategies 2 and 3 versus strategy 1 (current vaccination policy in Switzerland). Probabilities for clinical outcomes and medical resource utilization were derived from a real-world survey among Swiss pediatricians and general practitioners including 236 individuals with VZV infection, published information on varicella complications, and expert opinion. Costs of medical resource utilization represent official Swiss medical tariffs. The model predicts both universal childhood vaccination strategies to be more effective in reducing varicella disease burden compared to strategy 1. Economically, both universal childhood vaccination strategies with or without catch-up result in net savings from the societal perspective reflected by a benefit cost ratio (BCR) of 1.22 or 1.29, respectively. In contrast, the model predicts net costs from the payer perspective (BCR of 0.27 and 0.30, respectively). These economic findings are comparable to those reported from other similar evaluations. However, due to the recent recommendation for using a 2-dose varicella vaccination schedule, our economic results for Switzerland are somewhat less favorable than those for other country analyses in which a less expensive 1-dose vaccination regimen for toddlers has been studied.

[Mumps epidemic in vaccinated children in West Switzerland]

Since 1991, 6 years after the recommendation of universal childhood vaccination against measles, mumps, and rubella (MMR triple vaccine), Switzerland is confronted with a large number of mumps cases affecting both vaccinated and unvaccinated children. Up to 80% of the children suffering from mumps between 1991 and 1995 had previously been vaccinated, the majority with the Rubini vaccine strain. On the basis of a case-control study including 102 patients and 92 controls from the same pediatric population, a study of the humoral immune-response following vaccination with the Rubini vaccine in 6 young adult volunteers, and two different genetic studies, we investigated the complex problem of large scale vaccine failure in Switzerland. We conclude that the recently reported large number of Swiss mumps cases was caused by at least four interacting factors: 1. A vaccine coverage of 90-95% at the age of 2 years is necessary to interrupt mumps wild virus circulation. The nationwide vaccine coverage in Switzerland of some 80% in 27-36 month-old children is too low. 2. Primary vaccine failures (absence of seroconversion or unprotective low levels of neutralizing antibodies), as well as secondary vaccine failures due to the rapid decline of antibodies to mumps virus in our volunteers and controls, seem to be frequent after vaccination with the Rubini strain. 3. Despite its reported Swiss origin, the Rubini strain does not belong to the mumps virus lineages recently circulating in this area but is closely related to American mumps virus strains. 4. Differences in protein structure between the vaccine strain and the circulating wild type strains, and in particular a different neutralization epitope in the hemagglutinin neuraminidase protein, may additionally contribute to the lack of protection in vaccinated individuals.

Serotype epidemiology of invasive pneumococcal disease in Swiss adults: A nationwide population-based study.

BACKGROUND In Switzerland, the heptavalent (PCV7) and 13-valent pneumococcal conjugate vaccine (PCV13) were recommended for all infants aged <2 years in 2007 and 2011, respectively. Due to herd effects, a protective impact on the invasive pneumococcal disease (IPD) rates in adults had been expected. METHODS Within this study, data from the nationwide mandatory surveillance was analyzed for all adult patients ≥16 years with IPD of known serotype/serogroup during 2003-2012. Trend (for IPD cases from 2003 to 2012) and logistic regression analyses (2007-2010) were performed to identify changes in serotype distribution and to identify the association of serotypes with age, clinical manifestations, comorbidities and case fatality, respectively. FINDINGS The proportion of PCV7 serotypes among all IPD cases (n=7678) significantly declined in adults from 44.7% (2003) before to 16.7% (2012) after the recommendation of PCV7 (P<0.001). In contrast, the proportion of non-PCV7 serogroup/serotypes increased for non-PCV13 but also PCV13 serotypes (not included in PCV7) at the same time. Serotype distribution varied significantly across ages, clinical manifestations and comorbidities. Serotype was furthermore associated with case fatality (P=0.001). In a multivariable logistic regression model, analyzing single serotypes showed that case-fatality was increased for the serotypes 3 (P=0.008), 19A (P=0.03) and 19F (P=0.005), compared to serotype 1 and 7F. CONCLUSION There was a significant decline in PCV7 serotypes among adults with IPD in Switzerland after introduction of childhood vaccination with PCV7. Pneumococcal serotypes were associated with case fatality, age, clinical manifestation and comorbidities of IPD in adults. These results may prove useful for future vaccine recommendations for adults in Switzerland.