Unvaccinated residents who live in nursing homes where others have been vaccinated against COVID-19 have a low risk of contracting the virus, a research letter published May 19 in The New England Journal of Medicine suggests.
The analysis included 22,232 residents from 280 nursing homes in 21 states. Of those, 18,242 had received at least one dose of Pfizer or Moderna mRNA vaccine and 3,990 were not vaccinated.
Of those who had received the vaccine, more than 70 percent were fully vaccinated.
After a single dose, 4.5 percent of vaccinated residents became infected within the 14 days after receiving the shot. That dropped to 0.3 percent among fully vaccinated residents, researchers said.
Infections also fell among unvaccinated residents in the same nursing homes. After the facilities' first vaccination clinic, 4.3 percent of residents who didn't get the shot contracted COVID-19 within 14 days, dropping to 0.3 percent after 42 days.
Most recorded infections across both study groups were asymptomatic, according to the research letter.
"These findings show the real-world effectiveness of the mRNA vaccines in reducing the incidence of asymptomatic and symptomatic SARS-CoV-2 infections in a vulnerable nursing home population," researchers said. "Reduced incidence of infection among unvaccinated residents suggests that robust vaccine coverage among residents and staff, together with the continued use of face masks and other infection-control measures, is more likely to afford protection for small numbers of unvaccinated residents in congregate settings."