On Oct. 19, 2021, National Science Foundation funded scientists at the Yale School of Public Health and the University of North Carolina at Charlotte reported that strong protection following natural infection from COVID-19 was short-lived.

“Reinfection can reasonably happen in three months or less,” said Jeffrey Townsend of Yale, the study’s lead author. “Therefore, those who have been naturally infected should get vaccinated. Previous infection alone can offer very little long-term protection against subsequent infections.”

The study, published in the journal The Lancet Microbe , is the first to determine the likelihood of reinfection following natural infection and without vaccination.

The team analyzed known reinfection and immunological data from the close viral relatives of SARS-CoV-2 that cause common colds, along with immunological data from SARS-CoV-1 and Middle East Respiratory Syndrome. Leveraging evolutionary principles, the team was able to model the risk of COVID-19 reinfection over time.

Reinfections can and have happened even shortly after recovery, the researchers said. And they will become increasingly common as immunity wanes and new SARS-CoV-2 variants arise.tly after recovery, the researchers said. And they will become increasingly common as immunity wanes and new SARS-CoV-2 variants arise.