Prevalence of antibodies and humoral response after seasonal trivalent vaccination against influenza B lineages in an elderly population of Spain

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.