UW Study

Catching COVID Provides Protection from Its Worst Effects – UW Study

Past infection with COVID-19 offers permanent temporary protection against severe corona virus disease – regardless of variant, a new study has found.

Although natural immunity offers protection against COVID, the results have not discouraged vaccination, which is still the best way to prevent serious illness, said the experts involved in the study.

University of Washington researchers call their study, published Feb. 16 in The Lancet, the most comprehensive evidence yet showing natural immune protection against COVID.

The protection that natural immunity offers against hospitalization and death from COVID lasts for nearly a year, according to the study. Specifically, the risk of someone needing hospital treatment with the virus or of dying from it was 88% lower over at least 10 months.

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COVID infection has also been shown to protect against reinfection, symptoms during infection, and serious disease associated with the virus’ “ancestral” variants — namely the alpha, delta, and original Omicron strains, according to the study.

1 variant,” says a press release about the study.

The findings are based on a meta-analysis of 65 studies from 19 countries, including the US, UK, Canada, India and Norway, to assess the effectiveness of previous COVID infection in protecting a person. This includes studies examining reinfection with COVID in unvaccinated individuals.

Data on newer XBB omicron variants or their sub-lines were not examined in this study. The XBB.1.5 omicron variant is the most dominant in the US, according to data from the Centers for Disease Control and Prevention.

Vaccination is the safest way to acquire immunity, while acquiring natural immunity must be balanced against the risks of serious illness and death associated with initial infection, said Stephen Lim, the study’s lead author and a professor in the Department of Health Indicators. Das said the University of Washington Sciences in a statement.

If a person was previously infected with a non-omicron variant of the corona virus, protection from subsequent omicron infections was significantly lower, the study found.

However, if a person had been previously infected with Omicron, there was a greater chance of being protected from future Omicron infection – but not for sub variants BA.4 and BA.5, the researchers wrote. This confirms the greater immune escape associated with this particular sub variant.

To fully understand a person’s immune profile and risks from COVID-19, public health decision-makers need to consider natural immunity and vaccination status, said Dr. Caroline Stein, a co-author of the study, in a statement.

Such decisions, the researchers said, apply to guidelines for when people should receive COVID vaccine doses, including booster shots, the researchers wrote.

Limitations of the study included that fewer studies performed by the included authors had data on the original Omicron strains and their derivatives.

The work warrants further studies examining the protection provided by COVID vaccines and infection. This highlights how more studies have been published analyzing vaccine effectiveness versus COVID infection. This study was funded by the Bill and Melinda Gates Foundation.