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shiruken t1_j8ecsld wrote

This is a little tricky since the OP's study was conducted over a long period of time prior to the existence of the bivalent boosters designed for the Omicron variant, which partially evaded the immunity conferred by the original vaccines and/or infection with earlier strains of SARS-CoV-2.

The CDC publishes a tracker that is updated monthly showing the rates of COVID-19 cases and deaths by vaccination status. In December 2022, people aged 5+ who were vaccinated with an updated (bivalent) booster had 3.1x lower risk of testing positive for COVID-19 compared to unvaccinated people. People aged 5+ who were vaccinated without the updated booster only had 2.4x lower risk compared to unvaccinated.

A recent peer-reviewed study by the CDC found that the bivalent boosters from both Pfizer-BioNTech and Moderna were 48% effective against symptomatic infection from the current predominant omicron subvariant. Note that this effectiveness was calculated relative to fully vaccinated individuals without the bivalent booster dose, so the effectiveness relative to unvaccinated individuals would be even higher (but was beyond the scope of the study).

For more information about vaccine effectiveness, see this comprehensive list maintained by the CDC.

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