Image of older adult coughing into hand as companion looks pats his back
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Vaccinations and infection control measures may not entirely protect nursing homes from COVID-19 outbreaks — especially when staff members are unvaccinated, according to two new studies from France.

One study followed an outbreak that occurred in a single nursing home one month after it had fully vaccinated 75% of its residents and half of its staff with Pfizer-BioNTech shots. During the seven-week outbreak, 26% of residents and 22% of staff members were infected by the SARS-CoV-2 virus. Twelve out of 24 infected residents had not been fully vaccinated. All were older than uninfected residents, with an average age of 91 compared to 87, respectively.

Unvaccinated residents were three times more likely to develop COVID-19 than those who had had two doses of the vaccine. But the vaccine’s effectiveness in the elderly residents was estimated to be 68%, the researchers said. This is lower than the 95% efficacy in elders that Pfizer reported shortly before the shot’s rollout, but appears to be in line with other recent, real-world studies.

None of the infected staff members had been vaccinated.

Staff cases precede outbreak

In another study of nursing homes in the French Alps, meanwhile, investigators found that cases among staff were, in fact, the only predictor of an outbreak among residents.

Not only did nursing homes’ characteristics seem to have no effect — neither did any of the facilities’ hygiene measures. The homes all had similar hygiene measures, however, which made it difficult to compare effects, the researchers said. 

In fact, the findings suggest that in nursing homes with strict hygiene measures, resident outbreaks are likely to be traced to staff members only, and not facility size, ratio of staff to residents, or the use of temporary workers, the researchers concluded.

“We found that apart from staff infections, nothing influenced the occurrence of outbreaks and so, during the national lockdown, staff were the likely source of COVID-19 outbreaks among nursing home residents,” said Emilie Piet, a professor at the Annecy Genevois Hospital Centre, France.

U.S. situation

The results may mirror the national experience in the United States. States with higher rates of nursing home vaccinations have lower rates of COVID-19 cases and/or deaths among residents and fewer COVID-19 cases among staff, according to the Centers for Disease Control and Prevention. 

Infection rates are also going up in the overall U.S. population, with new hot spots driven by low vaccination rates in some areas of the South, the Midwest and West, according to a National Public Radio report. Vaccinations have slowed, meanwhile, and the Delta variant is spreading quickly. 

“I think we should brace ourselves to see case increases, particularly in unvaccinated populations,” Jennifer Nuzzo, of the Johns Hopkins Center for Health Security told the news outlet.

The United States has come a long way in protecting nursing home residents and staff, David Grabowski, Ph.D., a healthcare policy expert at Harvard Medical School and long-term care industry expert, noted in a July 8 twitter post. “Vaccines work!” he wrote. “But low vax rates in some areas and/or facilities suggest there is work left to do.”

The studies were presented at the European Congress of Clinical Microbiology & Infectious Diseases (ECCMID), held online this year.