Effectiveness of the COVID-19 bivalent vaccine.
Risk of COVID-19 increased with time since the most recent prior COVID-19 episode and, more importantly, with the number of vaccine doses previously received, which is then explained away with a multivariable analysis as a benefit.
Cumulative incidence of COVID increased with time since most recent COVID exposure, understandably.
Cumulative incidence of COVID also increased with the number of vaccine doses previously received, not as understandably. In other words, the most vaccinated had the highest COVID incidents, and the least vaccinated or unvaccinated had the least.
https://www.medrxiv.org/content/10.1101/2022.12.17.22283625v1