Prior Covid offers less protection vs Omicron; mRNA booster shot efficacy declines within months

Prior Covid offers less protection vs Omicron; mRNA booster shot efficacy declines within months

Reuters

The following is a summary of some recent studies on Covid-19. They include research that warrants further study to corroborate the findings and that has yet to be certified by peer review.

Previous Covid-19 less protective against Omicron variant

The immune response to Covid-19 helps protect against reinfection, but that protection is weaker against Omicron than it was against earlier variants of the coronavirus, according to new data.

A previous SARS-CoV-2 infection protects against Omicron reinfection only 56% of the time, researchers found in a review of national data in Qatar. Having had Covid was 90.2% effective against reinfection with the Alpha variant, 85.7% effective against a Beta variant reinfection, and 92% effective against Delta reinfection, researchers reported on Wednesday in The New England Journal of Medicine.

As was the case with reinfection due to earlier variants, however, "the protection of previous infection against hospitalization or death caused by reinfection (with Omicron) appeared to be robust," they said. In cases of reinfection with Omicron, for example, the immune response to previous infection was 87.8% effective at preventing the second infection from progressing to severe or critical illness or death.

mRNA vaccine booster protection declines within months

Protection provided by booster shots of the mRNA