(HealthDay News) — Among elderly veterans with a high burden of comorbidity, messenger RNA (mRNA) COVID-19 vaccination is 69% effective against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection and 86% effective against SARS-CoV-2-related death, according to a study published online in the Annals of Internal Medicine.

George N. Ioannou, BMBCh, from the University of Washington in Seattle, and colleagues examined the effectiveness of mRNA COVID-19 vaccines among 5,766,638 US persons receiving care in the Veterans Affairs health care system. A total of 2,099,871 who received at least 1 dose of the Moderna or Pfizer-BioNTech COVID-19 vaccine from Dec. 11, 2020, to March 25, 2021, were matched to unvaccinated controls in a 1:1 ratio.

The groups were well matched; individuals were predominantly male and had advanced age (mean, 68.7 years), diverse racial and ethnic distribution, and considerable comorbidity burden. The researchers found that at 7 or more days after the second dose, vaccine effectiveness was 69% against SARS-CoV-2 infection and 86% against SARS-CoV-2-related death. There was a decrease in vaccine effectiveness with increasing age and comorbidity burden.


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“In an elderly population of US veterans with high comorbidity burden, COVID-19 vaccine effectiveness against infection was substantially lower than previously reported but effectiveness against death was very high,” the authors write.

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