SARS-CoV-2 vaccine protection and deaths among US veterans during 2021
We report SARS-CoV-2 vaccine effectiveness against infection (VE-I) and death (VE-D) by vaccine type (n = 780,225) in the Veterans Health Administration, covering 2.7% of the U.S. population. From February to October 2021, VE-I declined from 87.9% to 48.1%, and the decline was greatest for the Janssen vaccine resulting in a VE-I of 13.1%. Although breakthrough infection increased risk of death, vaccination remained protective against death in persons who became infected during the Delta surge. From July to October 2021, VE-D for age 65 years was 73.0% for Janssen, 81.5% for Moderna, and 84.3% for Pfizer-BioNTech; VE-D for age ≥65 years was 52.2% for Janssen, 75.5% for Moderna, and 70.1% for Pfizer-BioNTech. Findings support continued efforts to increase vaccination, booster campaigns, and multiple, additional layers of protection against infection.
As shown in Fig. 2, risk of infection accelerated in both unvaccinated and fully vaccinated Veterans beginning in July 2021 and through September 2021, consistent with the time dependence observed in the Cox proportional hazards models. This pattern was similar across age groups, and risk of infection was highest for unvaccinated Veterans. Veterans who were fully vaccinated with the Moderna vaccine had the lowest risk of infection, followed closely by those who received the Pfizer-BioNTech vaccine, then those who received the Janssen vaccine.
Risk of death after SARS-CoV-2 infection was highest in unvaccinated Veterans regardless of age and comorbidity (Fig. 3). However, breakthrough infections were not benign, as shown by the higher risk of death in fully vaccinated Veterans who became infected compared to vaccinated Veterans who remained infection-free.
We observed similar results when examining the time period corresponding to the dominance of the Delta variant (fig. S1). Specifically, among those with a positive PCR test on or after July 1, 2021, vaccination was protective against death, although with some differences by age and vaccine type. For age <65 years, vaccine effectiveness against death (VE-D) was 81.7% (95% CI: 75.7% to 86.2%) for any vaccine; 73.0% (95% CI: 52.0% to 84.8%) for Janssen; 81.5% (95% CI: 70.7% to 88.4%) for Moderna; and 84.3% (95% CI: 76.3% to 89.7%) for Pfizer-BioNTech. For age ≥65 years, VE-D was 71.6% (95% CI: 68.6% to 74.2%) for any vaccine; 52.2% (95% CI: 37.2% to 63.6%) for Janssen; 75.5% (95% CI: 71.8% to 78.7%) for Moderna; and 70.1% (95% CI: 66.1% to 73.6%) for Pfizer-BioNTech.