A COVID-19 outbreak in a French nursing home—where 95% of residents but only a third of healthcare workers were fully vaccinated— infected nearly a quarter of residents and 12% of staff, finds a study today in JAMA Network Open.
Nursing home residents may be particularly vulnerable to COVID-19 infections and complications owing to impaired immune function tied to advanced age, congregate living, exposure to rotating unvaccinated healthcare personnel, weaker antibody response to vaccination, and underlying medical conditions such as malnutrition, diabetes, and cancer, the study authors noted.
No deaths among vaccinated
The outbreak occurred in a 77-bed nursing home in Biscarrosse, a town in southwest France, several weeks after the vast majority of residents received two doses of the Pfizer/BioNTech COVID-19 vaccine in January and February.
Of 74 total residents (mean age, 87.8 years; 22.2% men), 70 residents (95%) had received two doses of vaccine at least 14 days before the outbreak, while 2 (2.7%) had received one dose.
The first resident was infected by an initially asymptomatic visitor who informed the nursing after testing positive for COVID-19 4 days later. Seventeen of 74 residents (23.0%) were diagnosed as having COVID-19, of whom 5 were men and 12 were women. One was unvaccinated, two were partially vaccinated, and 14 were fully vaccinated.
Eight residents became severely ill, two were hospitalized, and the one unvaccinated resident died.
Vaccine may not be enough to protect vulnerable
Of the 102 healthcare workers, 34 (33.3%) were vaccinated, and 68 (66.7%) were unvaccinated. Twelve (11.8%) workers tested positive for COVID-19, five of whom developed symptoms; none had severe disease. Among the 68 unvaccinated staff members, 9 (13.2%) were infected, as were 3 (8.8%) vaccinated workers, one after full vaccination with the Pfizer vaccine and two after partial vaccination with the AstraZeneca/Oxford vaccine.
All infections were attributed to the SARS-CoV-2 Alpha (B117) variant. "To our knowledge, this is the first outbreak due to the B.1.1.7 COVID-19 variant described among individuals well vaccinated against SARS-CoV-2," the researchers wrote. They also noted an April 30 study in Morbidity and Mortality Weekly Report on an outbreak of an earlier SARS-CoV-2 variant in a US nursing home where 90% of residents were fully vaccinated.
The authors called for further research into ways to improve the efficacy of COVID-19 vaccines for nursing home residents. "Our study’s findings suggest that SARS-CoV-2 vaccination may not be sufficient as the sole means to prevent COVID-19 among [nursing home] residents and that other prevention measures should not be abandoned yet in these settings," they wrote.