ViVa 28 feature: Universal influenza vaccines – more than just “broader immunity”

Why We Need a Universal Influenza Vaccine Every year, millions of people roll up their sleeves for a flu shot, and every year, that same shot needs reformulating. This isn’t bureaucratic inefficiency — it’s dictated by biology. The moving target problem. Influenza viruses undergo continuous antigenic drift: small, incremental mutations in the surface proteins hemagglutinin (HA) and neuraminidase (NA) that gradually erode the ability of existing antibodies to recognize the virus. Because these mutations accumulate unpredictably, the WHO must convene expert panels twice a year to guess which strains will dominate the next season and reformulate vaccines accordingly. When that guess is wrong—as happened in the UK’s 2014-2015 season, when vaccine effectiveness against the drifted H3N2 strain fell to just 3%, compared to a typical 50%—population-level protection can collapse almost entirely. Rare but catastrophic antigenic shift events, where an animal-origin virus introduces an entirely novel HA/NA combination, pose an even greater pandemic...