Age-related prevalence of cross-reactive antibodies against influenza A(H3N2) variant virus, Germany, 2003 to 2010

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Age-related prevalence of cross-reactive antibodies against influenza A(H3N2) variant virus, Germany, 2003 to 2010

To estimate susceptibility to the swine-origin influenza A(H3N2) variant virus (A(H3N2)v) in the German population, we investigated cross-reactive antibodies against this virus and factors associated with seroprotective titre using sera from representative health examination surveys of children and adolescents (n = 815, 2003–06) and adults (n = 600, 2008–10). Antibodies were assessed by haemagglutination inhibition assay (HI); in our study an HI titre ≥ 40 was defined as seroprotective. We investigated associated factors by multivariable logistic regression. Overall, 41% (95% confidence interval (CI): 37–45) of children and adolescents and 39% (95% CI: 34–44) of adults had seroprotective titres. The proportion of people with seroprotective titre was lowest among children younger than 10 years (15%; 95% CI: 7–30) and highest among adults aged 18 to 29 years (59%; 95% CI: 49–67). Prior influenza vaccination was associated with higher odds of having seroprotective titre (odds ratio (OR) for children and adolescents: 3.4; 95% CI: 1.8–6.5; OR for adults: 2.4; 95% CI: 1.7–3.4). Young children showed the highest and young adults the lowest susceptibility to the A(H3N2)v virus. Our results suggest that initial exposure to circulating seasonal influenza viruses may predict long-term cross-reactivity that may be enhanced by seasonal influenza vaccination.

Avian influenza A(H5N1) in humans: new insights from a line list of World Health Organization confirmed cases, September 2006 to August 2010

The threat of avian influenza (AI) viruses to humans in Europe in 2005 prompted the Robert Koch Institute to establish a routine monitoring instrument condensing information on all human AI cases worldwide reported from the World Health Organization (WHO) and other sources into a line list for further analysis. The 235 confirmed AI cases captured from September 2006 to August 2010 had a case fatality rate of 56% (132/235), ranging from 28% (27/98) in Egypt to 87% (71/82) in Indonesia. In a multivariable analysis, odds of dying increased by 33% with each day that passed from symptom onset until hospitalisation (OR: 1.33, p=0.002). In relation to children of 0–9 years, odds of fatal outcome were more than six times higher in 10–19 year-olds and 20–29 year-olds (OR: 6.06, 95% CI: 1.89–19.48, p=0.002 and OR: 6.16, 95% CI: 2.05– 18.53, p=0.001, respectively), and nearly five times higher in patients of 30 years and older (OR: 4.71, 95% CI: 1.56–14.27, p=0.006) irrespective of the country, which had notified WHO of the cases. The situation in Egypt was special in that case number and incidence in children were more than twice as high as in any other age group or country. With this study, we show that data from the public domain yield important epidemiological information on the global AI situation. This approach to establish a line list is time-consuming but a line list is a prerequisite to such evaluations. We thus would like to encourage the placing of a publicly accessible line list of anonymised human AI cases, e.g. directly by WHO. This might enhance our understanding of AI in humans and permit the rapid detection of changes in its epidemiology with implications for human health.

Avian influenza A(H5N1) in humans: new insights from a line list of World Health Organization confirmed cases, September 2006 to August 2010

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Comparative varicella vaccine effectiveness during outbreaks in day-care centres

BACKGROUND

Routine varicella vaccination for children >11 months was introduced in Germany in 2004 with three different vaccine brands available. In 2008 and 2009, we investigated seven varicella outbreaks in day-care centres (DCC).

METHODS

Varicella disease and vaccination status of 1084 children was reviewed to evaluate vaccination coverage (VC), brand-specific varicella vaccine effectiveness (VE), and risk factors of breakthrough varicella (BV, >42 days after vaccination). A case was defined as a child with acute onset of varicella attending one of the respective DCC at the time of outbreak. Children with a previous history of varicella, age<11 months, vaccinated at age<11 months or <42 days before disease onset or during the outbreak were excluded from VE and BV risk factors analyses (adjusted for gender, age and DCC).

FINDINGS

Of 631 children with available vaccination information, 392 (62%) were vaccinated at least once. Overall VE among 352 children eligible was 71% (95% confidence interval (CI) 57-81, p<0.001) and differed significantly by disease severity and number of doses administered. Risk for BV was higher for 1 dose of Varilrix (RR=2.8, 95%CI 1.0-7.8, p=0.05) or Priorix-Tetra (RR=2.4, 95%CI 0.7-8.3, p=0.18) but lower for 2 doses of Priorix-Tetra (RR=0.5, 95%CI 0.1-2.7, p=0.41) than for 1 dose of Varivax.

INTERPRETATION

Enhanced efforts to increase VC in Germany and 2 doses varicella vaccine might be successful to reduce the risk for BV. The evidence that VE and risk of BV are associated with vaccine brand needs further investigation.