In a recent scientific paper published in the journal Nature Microbiology, researchers replicated two objective trials using the Department of Veterans Affairs (VA) electronic health records (EHR) to compare the effectiveness of the third dose of BNT162b2 or acid messenger ribonucleic (mRNA) – 1273 vaccine among United States (US) veterans.
Study: Comparative efficacy of third doses of mRNA-based COVID-19 vaccines in US veterans. Image credit: Steve Heap/Shutterstock
background
There is a lack of direct comparative studies on the efficacy of a third booster dose of different mRNA technology-based coronavirus disease 2019 (COVID-19) vaccines. An ideal comparative effectiveness study of mRNA vaccines should cover racially diverse populations and assess potential differences in vaccine efficacy based on when an individual completed the primary vaccination series. Most importantly, these studies should take into account the time windows of the prevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants.
During the current SARS-CoV-2-induced pandemic, vaccination effectively reduced the burden of severe disease and death from COVID-19. Notably, booster doses of BNT162b2 and mRNA-1273 vaccines counteracted the decline in immunity and extended protection against novel highly transmissible SARS-CoV-2 variants. In one of their previous work on 439,684 US veterans, the researchers found that both mRNA-1273 and BNT162b2 reduced the risk of SARS-CoV-2 infection and severe disease outcomes during the prevalence of the SARS-CoV-2 Alpha variant.
About the study
In the present study, investigators matched recipients of BNT162b2 or mRNA-1273 vaccines in a 1:1 ratio based on their risk factors to estimate their comparative effectiveness at 16 and nine weeks in the Delta-Omicron and Omicron periods , respectively, during five COVID. -19 results:
- reported SARS-CoV-2 infection,
- reported symptomatic SARS-CoV-2 infection,
- Hospitalization related to SARS-CoV-2 infection,
- admission to the intensive care unit (ICU) i
- death.
Veterans in the first simulated trial received the third dose of BNT162b2 or mRNA-1273 vaccines between October 20, 2021 and February 8, 2022. This period corresponded to the prevalence of Delta and Omicron variants of SARS- CoV-2. For each veteran in the primary analysis, the team began follow-up on the day of the third vaccination (baseline). It ended 16 weeks after initiation, death, or the end-of-study duration, i.e., February 15, 2022, as appropriate.
The veteran population of the second emulated trial received the third dose of either of the two COVID-19 mRNA vaccines between January 1 and March 1, 2022, the period of Omicron-only dominance. Average follow-up continued for nine weeks, during which the team documented 214 SARS-CoV-2 infections.
Results of the study
In the first simulated trial, 147,553 and 214,728 veterans received the third dose of BNT162b2 and mRNA-1273, respectively. Baseline characteristics of 65,196 BNT162b2 recipients matched with an equal number of mRNA-1273 recipients were comparable compared to the eligible population. The median age of this veteran population was 70 years, 96% were male, and 24% were black.
During the 16-week follow-up spanning Delta and Omicron prevalence, researchers documented 2,994 SARS-CoV-2 infections, of which 200 were symptomatic cases of COVID-19, 194 required hospitalization, 52 required admission to the ICU and 22 resulted in death. During this time, the estimated risk of reported infection for the third dose of BNT162b2 and mRNA-1273 was 353.9 and 308.5 events per 10,000 individuals, respectively.
In the second emulated trial, 25,557 and 36,809 eligible veterans received the third dose of BNT162b2-1273 mRNA, respectively. As in the first trial, the matched population consisted of 7,894 BNT162b2 recipients and an equal number of mRNA-1273 recipients with comparable baseline demographic and clinical characteristics relative to the eligible population. They had a higher proportion of men and whites.
During nine weeks of follow-up amid Omicron predominance, the estimated risk of documented SARS-CoV-2 infection was greater with a third dose of BNT162b2 vaccine versus mRNA-1273. Consequently, the estimated hazard ratio was 1.57, presented as events per 10,000 individuals.
Conclusions
The present study remarkably showed the comparative effect of the third (booster) dose of two mRNA vaccines, BNT162b2 and mRNA-1272, among a national cohort of US veterans. Both vaccines reduced the absolute risks of breakthrough SARS-CoV-2 infections and severe COVID-19 outcomes. However, mRNA-1273 recipients had a lower risk of adverse events related to COVID-19 during 16 weeks of follow-up than mRNA-1273 vaccine recipients, particularly for SARS-CoV-2 infections notified Findings remained comparable between periods spanning Delta and Omicron predominance and Omicron predominance alone. The authors advocated continued evaluation of the comparative efficacy and safety of additional (booster) doses of COVID-19 mRNA vaccines in the future.
Journal reference:
- Barbra A. Dickerman, Hanna Gerlovin, Arin L. Madenci, Michael J. Figueroa Muñez, Jessica K. Wise, Nimish Adhikari, Brian R. Ferolito, Katherine E. Kurgansky, David R. Gagnon, Kelly Cho, Juan P. Casas & Miguel A. Hernán, Comparative effectiveness of third doses of mRNA-based COVID-19 vaccines in US veterans. Nat Microbiol (2023). DOI: https://doi.org/10.1038/s41564-022-01272-z,