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However, the study was conducted before the surge of the highly transmissible Omicron variant.
"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 study author Dr. Ari Robicsek. He is chief medical analytics officer for the Providence health system, which operates in the western United States.
"That said, vaccination is a considerably safer way to acquire that immunity," Robicsek added in a health system news release.
For the study, the investigators analyzed data from more than 100,000 adults tested for the coronavirus at 1,300 care sites in the Providence health system between Oct. 1, 2020 and Nov. 1, 2021.
Prior COVID-19 infection in unvaccinated people was 85% protective against reinfection and 88% protective against hospitalization, the findings showed.
Protection from reinfection lasted for up to nine months after initial infection, which was the longest amount of time that patients were followed, the researchers said.
The study was published online April 20 in JAMA Network Open.
"This data is key to helping us understand the strength and longevity of natural immunity, and allows us to compare the effectiveness of a prior infection with mRNA vaccines," according to Dr. Amy Compton-Phillips, Providence's chief clinical officer.
"The results provide new insight into the length of protection following an initial infection among the unvaccinated population and could have important implications for vaccination guidelines and public health policy," she added.
SOURCE: Providence Health & Services, news release, April 20, 2022
By Robert Preidt HealthDay Reporter
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