Seasonal influenza vaccines induced high levels of neutralizing cross-reactive antibody responses against different genetic group influenza A(H1N1)pdm09 viruses

: Anu Haveri, Niina Ikonen, Anu Kantele, Veli-Jukka Anttila, Eeva Ruotsalainen, Carita Savolainen-Kopra, Ilkka Julkunen

Publisher: ELSEVIER SCI LTD

: 2019

: Vaccine

: VACCINE

: 37

: 20

: 2731

: 2740

: 10

: 0264-410X

: 1873-2518

DOI: https://doi.org/10.1016/j.vaccine.2019.03.078

Influenza A(H1N1)pdm09 viruses have been circulating throughout the world since the 2009 pandemic. A/California/07/2009 (H1N1) virus was included in seasonal influenza vaccines for seven years altogether, providing a great opportunity to analyse vaccine-induced immunity in relation to the postpandemic evolution of the A(H1N1)pdm09 virus. Serum antibodies against various epidemic strains of influenza A (H1N1)pdm09 viruses were measured among health care workers (HCWs) by haemagglutination inhibition and microneutralization tests before and after 2010 and 2012 seasonal influenza vaccinations. We detected high responses of vaccine-induced neutralizing antibodies to six distinct genetic groups. Our results indicate antigenic similarity between vaccine and circulating A(H1N1)pdm09 strains, and substantial vaccine-induced immunity against circulating epidemic viruses.