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Selected Works of Howard Smithline MD
Article
Effectiveness of a bivalent mRNA vaccine dose against symptomatic SARS-CoV-2 infection among U.S. Healthcare personnel, September 2022-May 2023
All Scholarly Works
  • Howard Smithline, Baystate Health
Link
Document Type
Article, Peer-reviewed
Publication Date
11-1-2023
Disciplines
Abstract

Background: Bivalent mRNA vaccines were recommended since September 2022. However, coverage with a recent vaccine dose has been limited, and there are few robust estimates of bivalent VE against symptomatic SARS-CoV-2 infection (COVID-19). We estimated VE of a bivalent mRNA vaccine dose against COVID-19 among eligible U.S. healthcare personnel who had previously received monovalent mRNA vaccine doses.

Methods: We conducted a case-control study in 22 U.S. states, and enrolled healthcare personnel with COVID-19 (case-participants) or without COVID-19 (control-participants) during September 2022-May 2023. Participants were considered eligible for a bivalent mRNA dose if they had received 2-4 monovalent (ancestral-strain) mRNA vaccine doses, and were ≥67 days after the most recent vaccine dose. We estimated VE of a bivalent mRNA dose using conditional logistic regression, accounting for matching by region and four-week calendar period. We adjusted estimates for age group, sex, race and ethnicity, educational level, underlying health conditions, community COVID-19 exposure, prior SARS-CoV-2 infection, and days since the last monovalent mRNA dose.

Results: Among 3,647 healthcare personnel, 1,528 were included as case-participants and 2,119 as control-participants. Participants received their last monovalent mRNA dose a median of 404 days previously; 1,234 (33.8%) also received a bivalent mRNA dose a median of 93 days previously. Overall, VE of a bivalent dose was 34.1% (95% CI, 22.6%-43.9%) against COVID-19 and was similar by product, days since last monovalent dose, number of prior doses, age group, and presence of underlying health conditions. However, VE declined from 54.8% (95% CI, 40.7%-65.6%) after 7-59 days to 21.6% (95% CI 5.6%-34.9%) after ≥60 days.

Conclusions: Bivalent mRNA COVID-19 vaccines initially conferred approximately 55% protection against COVID-19 among U.S. healthcare personnel. However, protection waned after two months. These findings indicate moderate initial protection against symptomatic SARS-CoV-2 infection by remaining up-to-date with COVID-19 vaccines.

Keywords: Bivalent; COVID-19; COVID-19 vaccines; Healthcare personnel; SARS-CoV-2; Vaccine effectiveness; mRNA vaccines.

PMID
37973512
Citation Information
Plumb ID, Briggs Hagen M, Wiegand R, Dumyati G, Myers C, Harland KK, Krishnadasan A, James Gist J, Abedi G, Fleming-Dutra KE, Chea N, Lee JE, Kellogg M, Edmundson A, Britton A, Wilson LE, Lovett SA, Ocampo V, Markus TM, Smithline HA, Hou PC, Lee LC, Mower W, Rwamwejo F, Steele MT, Lim SC, Schrading WA, Chinnock B, Beiser DG, Faine B, Haran JP, Nandi U, Chipman AK, LoVecchio F, Eucker S, Femling J, Fuller M, Rothman RE, Curlin ME, Talan DA, Mohr NM; Vaccine Effectiveness among Healthcare Personnel Study Team. Effectiveness of a bivalent mRNA vaccine dose against symptomatic SARS-CoV-2 infection among U.S. Healthcare personnel, September 2022-May 2023. Vaccine. 2023 Nov 14:S0264-410X(23)01287-2. doi: 10.1016/j.vaccine.2023.10.072. Epub ahead of print.