A COVID-19 outbreak at a nursing home in Kentucky was caused by a single employee who was not vaccinated, according to a new Centers for Disease Control & Prevention study, but the residents and employees who were vaccinated are many better protected.
The outbreak has been linked to dozens of infections in employees and residents, including 22 residents and workers who have already been vaccinated. The virus was introduced by a single employee who was not vaccinated and was not symptomatic.
However, the number of seizures was three to four times as high among vaccinated residents and employees as among those vaccinated, and the vaccinated staff and residents were significantly less likely to experience symptoms or require hospitalization.
During the outbreak, 46 cases of COVID-19 were identified, according to the CDC, including cases in 26 residents, where 18 were fully vaccinated, and 20 health care workers, where four were vaccinated.
One vaccinated resident, who was infected 300 days earlier, was re-infected during the outbreak and died. Two residents who were not vaccinated also died.
The low rate of breakthrough infections, and the fact that most breakthrough infections were asymptomatic, underscore the importance of vaccinating residents and staff of nursing homes.
The coronavirus is likely to be introduced into a nursing home by an infected staff member who regularly enters and leaves the institution. In the CDC-surveyed nursing home in Kentucky, 90 percent of the 83 residents were vaccinated, but only half of the 116 staff were at the time of the March outbreak.
The low acceptance of vaccination among workers in nursing homes nationwide was a challenge, which could increase the likelihood of the introduction and dispatch of COVID-19 within a facility, the CDC said.
Vaccination of workers and residents ‘is critical to reducing the risk of SARS-CoV-2 introduction, transmission and serious outcomes’ in nursing homes, the CDC said.
The outbreak concerns the R.1 variant of the virus, which the CDC does not mention as a worrying variant, but still contains multiple mutations in the peak protein that can make vaccinations less effective.
The Pfizer-BioNTech vaccine shows efficacy of 66 percent for residents against infection, and 75.9 percent for employees.
CDC acknowledged that both numbers are lower than those of Israel’s national vaccination program. This may be due to reduced protection against the R.1 variant, but it may also be due to a small sample size and the higher exposure risk associated with an outbreak in a municipal environment.
However, the CDC said that vaccinated residents and staff had 87 percent less symptomatic COVID-19 compared to those who were not vaccinated.
Meanwhile, a separate study launched simultaneously from nursing homes in Chicago found that among the 627 people with COVID-19 infections in 75 nursing homes, only 22 infections were found in people who were vaccinated, and that there was no secondary transmission of the facility did not take place.
Nearly two-thirds of the breakthrough infections were asymptomatic. Yet two residents were admitted to the hospital due to COVID-19, and one died.
The CDC said the study in Chicago shows that nursing homes should continue to follow recommended infection and control practices, and promote high vaccination coverage among residents and staff members.