Vaccination accelerates the race of influenza virus against collective immunity.

Respiratory viruses persist in a population, because their rapid evolution allows them to escape recognition by antibodies in previously-infected individuals. To optimize parameters of an effective vaccine, an epidemiological model of a population infected with an evolving virus is coupled to a model of multi-locus evolution. Model parameters are informed from influenza virus data. The cases of overlapping and non-overlapping effect of consecutive vaccinations are considered. The results predict that vaccination will accelerate viral evolution and may even increase infection incidence, unless one of two scenarios takes place: either antibodies elicited by vaccine are more broadly neutralizing than antibodies to natural infection, or the vaccine vector lies slightly ahead of the dominant virus variant in the evolutionary trajectory. These results suggest that the probabilistic prognosis of virus evolution represents a promising strategy of vaccine improvement complementing the search for broadly-neutralizing vaccines.