High levels of exposure to Covid virus may reduce protection from vaccination, prior infection: Study

High levels of exposure to the SARS-CoV-2 virus may reduce or overcome the protection that COVID-19 vaccination and prior infection provides, according to a study conducted in the US.

The findings, published recently in the journal Nature Communications, suggest that in densely crowded settings, control measures that reduce levels of exposure to the virus — such as masking, improved ventilation, and distancing — may afford additional benefit in preventing new infections among people who have been vaccinated or previously infected.

The study was performed to understand whether the immunity gained after vaccination or a prior infection was less effective or “leaky” in situations where people are exposed to high levels of the virus.