Seasonal influenza vaccines

Influenza is a vaccine preventable disease and influenza vaccines have been available for use in Europe since the 1960s.

A number of variants of the influenza viruses co-circulate each year. Immunity to the infecting influenza virus type develops following a natural influenza infection. However, there is little cross-immunity between influenza types/subtypes or lineages. This is why several influenza strains must be included into combination vaccines.

Due to the rapid virus evolution influenza viruses go through the combination vaccines must be updated yearly.

Currently most influenza vaccines used in the European Union/European Economic Area (EU/EEA) contain three different influenza strains (trivalent): two influenza A (H1N1 and H3N2 subtypes) and one influenza B (Victoria or Yamagata lineages).

Starting from the influenza season 2014-15 new quadrivalent combination vaccines containing four different influenza strains gradually are becoming available. These vaccines contain two influenza A (H1N1 and H3N2 subtypes) and two influenza B (Victoria and Yamagata lineages) strains.