Layton JB, Peetluk LS, Wong H, Jiao Y, Ogilvie RP, Miller M, Glazier-Essalmi A, Parambi RJ, Song J, Garcia de Albeniz Martinez X, Lloyd PC, Lo A, Kawai A, Weatherby L, Bell EJ, Yang G, Amend KL, Gruber JF, Clarke TC, Forshee RA, Anderson SA, Wernecke M, Matuska K, Chillarige Y, Anthony M, Seeger JD, Shoaibi A. Effectiveness of monovalent COVID-19 booster/additional vaccine doses in the United States. Presented at the 39th ICPE Annual Conference; August 27, 2023. Halifax, Canada. [abstract] Pharmacoepidemiol Drug Saf. 2023 Oct 12; 32(S1):608. doi: 10.1002/pds.5687

BACKGROUND: Monovalent booster or additional doses of COVID-19 (coronavirus disease 2019) vaccines were first authorized in the United States (US) in 2021, but their real-world effectiveness compared with a complete primary series without a booster/additional dose remains unclear.

OBJECTIVES: To evaluate the real-world effectiveness of receipt of a monovalent booster/additional dose of COVID-19 vaccine, by brand, compared with receiving a complete primary vaccine series without a booster dose in the US.

METHODS: Brand-specific cohorts of “boosted” individuals aged 12-64 years (depending on brand-specific age authorizations during the study period) receiving a COVID-19 booster/additional dose after a complete primary vaccine series were identified in Optum pre-adjudicated administrative insurance claims data linked with Immunization Information Systems from 10 US jurisdictions. Individuals with a complete primary series but without record of a booster/additional dose were matched 1-to-1 to boosted individuals on calendar date, US county and state, and clinical factors. COVID-19 diagnoses were identified from claims in any medical care setting or in the hospital/emergency department (ED) setting. Propensity score–weighted hazards ratios (HRs) and 95% confidence intervals (CIs) were estimated by vaccine brand using Cox proportional hazards models; relative vaccine effectiveness (VE) was estimated as 1 minus the HR, overall and within variant-specific eras and subgroups.

RESULTS: We identified 115,471 matched pairs for BNT162b2; 67,463 for mRNA-1273; and 1,718 for JNJ-7836735. Overall, for any medically diagnosed COVID-19, VE estimates ranged from 40% (JNJ-7836735) to 57% (mRNA-1273); against hospital/ED-diagnosed COVID-19, VE estimates ranged from 74% to 76%. VE was generally lower during the Omicron era than during the Delta era (e.g., for any medically-diagnosed COVID-19, VE ranged from 58% to 59% during the Delta era and ranged from 40% to 49% during the Omicron era).

CONCLUSIONS: Compared with a complete primary series without a booster/additional doses, the monovalent booster/additional doses provided additional effectiveness in real-world use for preventing medically diagnosed COVID-19, particularly hospital/ED-diagnosed COVID-19. Updated estimates of VE are needed in individuals receiving bivalent boosters and in time periods with new predominant viral variants.

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