Study: Natural immunity to COVID gives 97% protection against severe reinfection for many months

Protection against total infection wanes significantly, but "critical" or "fatal" COVID kept at bay.
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A German doctor tests a patient for infection, March 2022
A German doctor tests a patient for infection, March 2022
(picture alliance/Getty)

Researchers say in a newly released study that prior infection with COVID-19 offers long-lasting and comprehensive immunity against severe and fatal cases of the virus. 

The study, published online at medRxiv and not yet subject to peer review, was conducted by a team of researchers largely based out of Qatar. The scientists in the preprint stated "the future of the SARS-CoV-2 pandemic hinges on virus evolution and duration of immune protection of natural infection against reinfection."

They also said that while immunity derived from "natural infection" offers a relatively quickly-waning protection against re-infection, the durability of natural immunity against severe reinfections was robust and long-lasting. 

"Protection of natural infection against reinfection wanes and may diminish within a few years," the researchers observe in the paper, while "protection against severe reinfection remains very strong, with no evidence for waning, irrespective of variant, for over 14 months after primary infection."

"Effectiveness of primary infection against severe, critical, or fatal COVID-19 reinfection was 97.3%" over that time period, the paper states. 

The researchers to gather their data studied "duration of protection afforded by natural infection, the effect of viral immune evasion on duration of protection, and protection against severe reinfection” in Qatar from Feb. 28, 2020 to June 5, 2022.