Abstract

Twice yearly the WHO influenza vaccine strain selection committee meets to select which strains to include in the seasonal influenza vaccine for the upcoming season, trying to balance the need to update the vaccine to protect against upcoming antigenic variants and the need to maintain protection against current variants that may continue to circulate. Understanding antigenic variation and epidemiological trends features heavily in this process but an often under-emphasised component is how pre-existing immunity in the recipient population varies and influences these decisions. This talk will centre around our work to model and understand the role of population pre-vaccination immunity in determining optimal vaccine strain choices under such circumstances, including efforts to anticipate antigenic changes and get ahead of the evolutionary curve in a situation where time from vaccine strain selection to administration may be as long as 6-9 months.