Effectiveness of a Messenger RNA Vaccine Booster Dose Against Coronavirus Disease 2019 Among US Healthcare Personnel, October 2021-July 2022
Background: Protection against symptomatic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection (coronavirus disease 2019 [COVID-19]) can limit transmission and the risk of post-COVID conditions, and is particularly important among healthcare personnel. However, lower vaccine effectiveness (VE) has been reported since predominance of the Omicron SARS-CoV-2 variant.
Methods: We evaluated the VE of a monovalent messenger RNA (mRNA) booster dose against COVID-19 from October 2021 to June 2022 among US healthcare personnel. After matching case-participants with COVID-19 to control-participants by 2-week period and site, we used conditional logistic regression to estimate the VE of a booster dose compared with completing only 2 mRNA doses >150 days previously, adjusted for multiple covariates.
Results: Among 3279 case-participants and 3998 control-participants who had completed 2 mRNA doses, we estimated that the VE of a booster dose against COVID-19 declined from 86% (95% confidence interval, 81%-90%) during Delta predominance to 65% (58%-70%) during Omicron predominance. During Omicron predominance, VE declined from 73% (95% confidence interval, 67%-79%) 14-60 days after the booster dose, to 32% (4%-52%) ≥120 days after a booster dose. We found that VE was similar by age group, presence of underlying health conditions, and pregnancy status on the test date, as well as among immunocompromised participants.
Conclusions: A booster dose conferred substantial protection against COVID-19 among healthcare personnel. However, VE was lower during Omicron predominance, and waning effectiveness was observed 4 months after booster dose receipt during this period. Our findings support recommendations to stay up to date on recommended doses of COVID-19 vaccines for all those eligible.
Keywords: COVID-19; Omicron; SARS-CoV-2; healthcare personnel; vaccine effectiveness.
Plumb ID, Mohr NM, Hagen M, Wiegand R, Dumyati G, Harland KK, Krishnadasan A, Gist JJ, Abedi G, Fleming-Dutra KE, Chea N, Lee J, Barter D, Brackney M, Fridkin SK, Wilson LE, Lovett SA, Ocampo V, Phipps EC, Marcus TM, Smithline HA, Hou PC, Lee LC, Moran GJ, Krebs E, Steele MT, Lim SC, Schrading WA, Chinnock B, Beiser DG, Faine B, Haran JP, Nandi U, Chipman AK, LoVecchio F, Talan DA, Pilishvili T. Effectiveness of a Messenger RNA Vaccine Booster Dose Against Coronavirus Disease 2019 Among US Healthcare Personnel, October 2021-July 2022. Open Forum Infect Dis. 2023 Sep 8;10(10):ofad457. doi: 10.1093/ofid/ofad457.