Scientists from Weill Cornell Medicine-Qatar found that protection against omicron is the strongest with hybrid immunity.
The research is published in the New England Journal of Medicine and was conducted by Heba N. Altarawneh et al.
In the study, the team examined the effectiveness of BNT162b2 or mRNA-1273 vaccination, natural immunity due to the previous infection with nonomicron variants, and hybrid immunity against symptomatic omicron infection and severe, critical, or fatal COVID-19.
The researchers found that the effectiveness of previous infection alone was 46.1 percent against symptomatic BA.2 infection.
Vaccination with two doses of BNT162b2 and no previous infection had negligible effectiveness (−1.1 percent); the second dose had been received more than six months earlier among nearly all individuals.
The effectiveness was 52.2 percent for three doses of BNT162b2 and with no previous infection.
The effectiveness was 55.1 and 77.3 percent for two doses and three doses of BNT162b2, respectively, and previous infection.
Strong effectiveness (>70 percent) was seen against severe, critical, or fatal COVID-19 due to BA.2 infection for previous infection alone, BNT162b2 vaccination alone, and hybrid immunity.
The results were similar in analyses of effectiveness against BA.1 infection and vaccination with mRNA-1273.
The team says recent booster vaccination had moderate effectiveness, whereas hybrid immunity from previous infection and recent booster vaccination conferred the strongest protection against infection, at approximately 80 percent.
If you care about omicron, please read studies that previous COVID infections less protective against Omicron, and you need three COVID-19 exposures to get a broad immunity for omicron.
For more information about COVID, please see recent studies about 4 new COVID variants in New York City wastewater, and results showing why many people are against the COVID vaccine and masks.
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