Introduction: The aim of this study was to analyze the presence of antibodies against both Yamagata and Victoria influenza B lineages and to check the response after seasonal trivalent vaccination.
Materials and methods: Haemagglutination inhibition assays were performed with pre-and post-vaccination serum samples from 174 individuals ≥65 years of age vaccinated with seasonal trivalent influenza vaccines during the 2006-2007, 2008-2009, 2009-2010 and 2010-2011 vaccine campaigns.
Results: 33.9% of individuals showed pre-vaccine protective antibodies (≥1/40) against B/Yamagata lineage and 41.4% against B/Victoria lineage. The annual trivalent vaccine induced significant homologous seroconversion in 14-35.6% of individuals in each vaccine campaign.
Conclusions: The population ≥65 years has low-moderate seroprotection against B influenza lineages. Trivalent vaccination induced a slight increase of seroprotection. The trivalent vaccine should be administered to all individuals ≥65 years in all vaccine campaigns.
Keywords: Antibodies; Anticuerpos; Influenza B lineages; Linajes de gripe B; Trivalent influenza vaccination; Vacuna trivalente de gripe.
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