Antibodies Cross-Reactive to Influenza A (H3N2) Variant Virus and impact of 2010-11 Seasonal Influenza Vaccine on Cross-Reactive Antibodies-United States

摘要

Since August 2011, a total of 12 Human infections with influenza A (H3N2) variant viruses with genes from avian, swine, and human viruses (i.e., A [H3N2]v) that had acquired the M gene from influenza A (HlNl)pdm09 virus have been reported to CDC. Eleven of the cases occurred in children aged <10 years. In six cases, no history of recent exposure to swine was noted, suggesting that human-to-human transmission had occurred. This new gene constellation for A (H3N2)v viruses and its temporal association with an increase in human cases of A (H3N2)v highlight the need to better understand the risk for human infection with these viruses and the extent to which current seasonal vaccines might elicit cross-reactive antibodies to them. CDC conducted a preliminary analysis to evaluate the age-specific presence of serum cross-reactive antibody in U.S. populations vaccinated or not vaccinated with the 2010-11 seasonal trivalent influenza vaccine (TIV).