COVID Infection Provides Immunity Equal to Vaccination: Study

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Feb. 17, 2023 -- The natural immunity provided by a COVID infection protects a person against severe illness on a par with two doses of mRNA vaccine, a new study says. 

People who've been infected with COVID reduced their chances of hospitalization and death by 88% over 10 months compared to somebody who hasn't been infected, says the study, published in The Lancet

The natural immunity provided by infection was “at least as high, if not higher” than the immunity provided by two doses of Moderna or Pfizer mRNA vaccines against the ancestral, Alpha, Delta, and Omicron BA.1 variants, the study says. 

But protection against the BA.1 subvariant of Omicron was not as high – 36% at 10 months after infection, says the research team from the Institute for Health Metrics and Evaluation at the University of Washington.

The researchers examined 65 studies from 19 countries through Sept. 31, 2022. They did not study data about infection from Omicron XBB and its sub-lineages. People who had immunity from both infection and vaccination, known as hybrid immunity, were not studied. 

The findings don't mean people should skip the vaccines and get COVID on purpose, one of the researchers told NBC News

“The problem of saying 'I'm gonna get infected to get immunity' is you might be one of those people that end up in the hospital or die,” said Christopher Murray, MD, DPhil, director of the IHME. “Why would you take the risk when you can get immunity through vaccination quite safely?”

The findings could help people figure out the most effective time to get vaccinated or boosted and guide officials in setting policies on workplace vaccine mandates and rules for high-occupancy indoor settings, the study concludes.

This was the largest meta-analysis of immunity following infection to date, NBC News reports.