January 20, 2023
The Cleveland Clinic has published the results of an internal study they conducted on the effectiveness of the bivalent COVID injection. The study tracked the vaccine and infection status of 51,000 employees for the thirteen weeks after the bivalent booster became available.
The study showed that the bivalent booster is only 30% effective at preventing COVID infection. It also showed that those who have received a larger number of injections are at greater risk of becoming ill with COVID, a result which the study’s authors described as “unexpected” (though they did reference two other studies that showed the same result). In discussing their findings, the authors said:
The evolution of the SARS-CoV-2 virus necessitates a more nuanced approach to assessing the potential impact of vaccination than when the original vaccines were developed. Additional factors beyond vaccine effectiveness need to be considered. The association of increased risk of COVID-19 with higher numbers of prior vaccine doses in our study, was unexpected…We still have a lot to learn about protection from COVID-19 vaccination, and in addition to a vaccine’s effectiveness it is important to examine whether multiple vaccine doses given over time may not be having the beneficial effect that is generally assumed.
In conclusion, this study found an overall modest protective effect of the bivalent vaccine booster against COVID-19, among working-aged adults. The effect of multiple COVID-19 vaccine doses on future risk of COVID-19 needs further study.