Pandemic and seasonal H1N1 influenza hemagglutinin-specific T cell responses elicited by seasonal influenza vaccination

Understanding whether seasonal influenza vaccines can elicit antibody and T cell responses against the 2009 pandemic HI NI strain is important. We compared T cell and antibody responses elicited by trivalent inactivated influenza vaccine (TIV) and live attenuated influenza vaccine (LAIV) in healthy adults. Both vaccines boosted pre-existing T cells to the seasonal and pandemic hemagglutinin (HA) but responses were significantly greater following immunization with LAW. Antibody titers were significantly boosted only by TIV. The relationship between antibody and T cell responses and the effect of the magnitude of pre-existing immunity on vaccine-induced responses were also evaluated. Cross reactive T cell responses to the pandemic H1N1 HA existed among the cohort before the circulation of the virus to varying degrees and these responses were boosted by seasonal vaccination. (C) 2010 Elsevier Ltd. All rights reserved.