A new study published on Wednesday (April 20) in JAMA Network Open by investigators at Providence—one of the largest health systems in the United States—and the University of Chicago, found that the level of protection granted by a COVID-19 infection among unvaccinated adults was on par with the level of protection provided by mRNA vaccines, with natural immunity providing a longer window of protection.
“We found that, before the emergence of the Omicron variant, natural immunity provided a similar degree of protection against COVID-19 infection as mRNA vaccination,” said Ari Robicsek, M.D., Providence’s chief medical analytics officer and senior author of the study.
Conducted by a team of expert clinicians and scientists, the study examined data from over 100,000 patients tested for SARS-CoV-2 at 1,300 sites between October 1, 2020 and November 1, 2021.
The researchers observed that prior COVID-19 infection was 85% protective against reinfection and 88% protective against hospitalization, with protection from reinfection lasting for up to nine months following the initial infection, as far out as they were able to study.