Age-specific differences in influenza virus type and subtype distribution in the 2012/2013 season in 12 European countries

Abstract

SUMMARYThe epidemiology of seasonal influenza is influenced by age. During the influenza season, the European Influenza Surveillance Network (EISN) reports weekly virological and syndromic surveillance data [mostly influenza-like illness (ILI)] based on national networks of sentinel primary-care providers. Aggregated numbers by age group are available for ILI, but not linked to the virological data. At the end of the influenza season 2012/2013, all EISN laboratories were invited to submit a subset of their virological data for this season, including information on age. The analysis by age group suggests that the overall distribution of circulating (sub)types may mask substantial differences between age groups. Thus, in cases aged 5–14 years, 75% tested positive for influenza B virus whereas all other age groups had an even distribution of influenza A and B viruses. This means that the intepretation of syndromic surveillance data without age group-specific virological data may be misleading. Surveillance at the European level would benefit from the reporting of age-specific influenza data.

Molecular influenza surveillance at a tertiary university hospital during four consecutive seasons (2012–2016) in Catalonia, Spain

“…Therefore, some differences were found between influenza types (A vs B) or subtypes (H1pdm09 vs H3), or vice versa regarding the age and the clinical outcomes of influenza-confirmed cases, such as hospitalisation, ICU-admission, and mortality rates. In the present study, the population susceptible to FLUAV infection seemed to be older than that susceptible for FLUBV, although FLUAV was predominant in almost all age groups, except to 5-14-year-old group in whom FLUBV prevailed as previously reported by other authors [31,32]. On the other hand, while no differences were found between A(H1N1) pdm09 and A(H3N2), the distribution of cases by age groups was different.…”

Evaluating oseltamivir prescriptions in Centers for Medicare and Medicaid Services medical claims records as an indicator of seasonal influenza in the United States

“…24 Next, a second wave of influenza during the 2012-13 season was more prominent in the influenza virus data than in the CMS medical claims data (Figure 1). 25,26 Results from the MEM analyses of medical claims data agreed substantially with results from ILINet; however, they differed with respect to results from the influenza virus data (Table 3).…”

“…Conversely, influenza illnesses that do not come to medical attention are also absent from medical claims data. Therefore, the pathogenicity and virulence of circulating influenza viruses—which may differ between people 65 years old and older and younger people—affect our indicator in complex ways …”

Infections Caused by Influenza Viruses Among Children in Poland During the 2017/18 Epidemic Season

“…That is in line with the past results from other European research centers. In one of them, results from 12 European countries have been analyzed with reference to the 2012/13 season and the dominance of influenza B virus is reported in children aged 5-14 years (Beauté et al 2015). In another study, the relation between influenza virus type and subtypes and the age of children was determined.…”