Over the course of a person’s lifetime they will be infected with multiple strains of influenza virus, leaving a specific pattern of antibodies in their blood.
Researchers at the London School of Hygiene and Tropical Medicine took blood samples of 151 unvaccinated people in Southern China and analysed their antibody profile against nine strains of flu that circulated over the past 40 years. The results were used to refine a mathematical model that can estimate individual histories of infection.
Among the group analysed in PLOS Biology
(online, 3 March 2015), “young people seem to contract flu every other year on average, while adults over 30 seem to contract flu twice a decade”, says lead researcher Adam Kucharski. The model filters out properties of the immune response that can make analysis difficult, such as cross-reactivity between strains.