Publication Date
11-1-2024
Journal
Influenza and Other Respiratory Viruses
DOI
10.1111/irv.70027
PMID
39496339
PMCID
PMC11534416
PubMedCentral® Posted Date
11-4-2024
PubMedCentral® Full Text Version
Post-print
Published Open-Access
yes
Keywords
Humans, COVID-19, Hospitalization, COVID-19 Vaccines, Male, Female, United States, Middle Aged, Aged, Adult, Vaccine Efficacy, SARS-CoV-2, Case-Control Studies, Young Adult, Vaccination, Aged, 80 and over, Adolescent
Abstract
BACKGROUND: Assessments of COVID-19 vaccine effectiveness are needed to monitor the protection provided by updated vaccines against severe COVID-19. We evaluated the effectiveness of original monovalent and bivalent (ancestral strain and Omicron BA.4/5) COVID-19 vaccination against COVID-19-associated hospitalization and severe in-hospital outcomes.
METHODS: During September 8, 2022 to August 31, 2023, adults aged ≥ 18 years hospitalized with COVID-19-like illness were enrolled at 26 hospitals in 20 US states. Using a test-negative case-control design, we estimated vaccine effectiveness (VE) with multivariable logistic regression adjusted for age, sex, race/ethnicity, admission date, and geographic region.
RESULTS: Among 7028 patients, 2924 (41.6%) were COVID-19 case patients, and 4104 (58.4%) were control patients. Compared to unvaccinated patients, absolute VE against COVID-19-associated hospitalization was 6% (-7%-17%) for original monovalent doses only (median time since last dose [IQR] = 421 days [304-571]), 52% (39%-61%) for a bivalent dose received 7-89 days earlier, and 13% (-10%-31%) for a bivalent dose received 90-179 days earlier. Absolute VE against COVID-19-associated invasive mechanical ventilation or death was 51% (34%-63%) for original monovalent doses only, 61% (35%-77%) for a bivalent dose received 7-89 days earlier, and 50% (11%-71%) for a bivalent dose received 90-179 days earlier.
CONCLUSION: Bivalent vaccination provided protection against COVID-19-associated hospitalization and severe in-hospital outcomes within 3 months of receipt, followed by a decline in protection to a level similar to that remaining from previous original monovalent vaccination by 3-6 months. These results underscore the benefit of remaining up to date with recommended COVID-19 vaccines.
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