Seroprevalence of influenza A and B in German infants and adolescents

Abstract

The objective of this study was to provide seroepidemiological information on influenza A and B antibodies in children and adolescents. Viral immunoglobulin G antibodies were determined retrospectively using enzyme-linked immunosorbent assays in a group of 1,111 children and adolescents. Sera (809) from healthy adult blood donors served as controls. In children, the prevalence of antibodies against influenza A was 82.0% and against influenza B 9.6%, whereas in adults the prevalence of antibodies against influenza A was calculated as 99.4% and against influenza B 56.7%. After decline of maternal antibodies during the first year of life, there was an increase of prevalence of influenza A antibodies up to 100% by the age of 12 years. In contrast, only 1-2% of children up to 9 years had influenza B antibodies increasing to 25% by the age of 18 years and to 70% among adults aged 30 years. Children aged 0-6 years had significantly lower concentrations and >12-15-year-old adolescents had significantly higher concentrations of antibodies against influenza A than adults. For all age groups of children and adolescents, significantly lower antibody concentrations against influenza B were measured in comparison to the blood donor control group. In conclusion, the annual influenza vaccination in children and adolescents may improve considerably the protection against influenza virus infection occurring during epidemics.

Prevalence of antibodies against influenza A and B viruses in children in Germany, 2008 to 2010

“…Testing of defined serum samples from children [2], newborns and their mothers [22] by several commercial ELISAs, including the haemagglutination inhibition assay [23], revealed sensitivities ≥97% and no crossreactivities between influenza A and B virus or to other viral pathogens for the ELISAs used in this study. Both ELISAs were carried out manually and used for qualitative and semi-quantitative antibody testing.…”

“…To obtain data most widely representative for the whole population of children in Germany, nine different German regions were included. A recently published study on the influenza seroprevalence in Germany included only sera from children who lived in the German federal state Thuringia [2], and the results were not regarded as representative for the entire country. Furthermore, as that study used other serological methods than ours, the results are only comparable to a limited extent.…”

“…Children are one of the most vulnerable groups since they are often immunologically naïve when placentally transferred antibodies have disappeared after ca one year of life [2], and the contacts made by children favour infections by the respiratory route [3]. Thus, influenza has been shown to be an important cause of morbidity during childhood, with attack rates ranging from 20% to 30% during epidemics [4].…”

“…Therefore, seroepidemiological data on influenza A and B during childhood as a surrogate for type-specific priming are a fundamental prerequisite for the development of efficacious vaccination policies for children. To date, the available data are scarce, and restricted to regional sampling points [2] or virus strain-specific tests [17,18]. The seroprevalence against influenza A and B, determined by sensitive and specific type-specific ELISA, may be a good surrogate marker for immunological priming since strain-specific assays such as the haemagglutination inhibition test depend on carefully selected panels of virus antigens and may underestimate the true seroprevalence.…”

2012/13 influenza vaccine effectiveness against hospitalised influenza A(H1N1)pdm09, A(H3N2) and B: estimates from a European network of hospitals

“…[104] Data from serologic surveys have demonstrated that 15-45% of children are infected with an influenza virus each year, [105] and by the age of 6, most children have been infected with influenza viruses at least once. [106] Children infected with influenza will shed higher titers of virus during their illness and shed virus for longer periods of time compared with adults. [107,108] This finding, together with high rates of illness, suggests children are critical source in the transmission of influenza in communities and households, and sustain annual epidemics.…”