On Jan. 25, 2023, researchers at Oregon Health & Science University (OHSU) reported that Immunity from COVID-19 appears to gather strength with more time between vaccination and infection, a new laboratory study from researchers at Oregon Health & Science University suggested. The findings carry implications for vaccine recommendations as the pandemic transitions to an endemic state.

Researchers measured the antibody response in blood samples for a group of people who gained so-called “hybrid immunity” through two means: either vaccination followed by a breakthrough infection, or by getting vaccinated after contracting COVID-19. They measured the immune response in blood samples of 96 generally healthy OHSU employees and found that the immune response was uniformly stronger the longer the time period between vaccination and infection. The longest interval measured was 404 days.

Their findings suggest that vaccine boosters should be spaced no more frequently than a year apart, at least among healthy people. The study was published online in the Journal for Clinical Investigation Insight.