An outbreak of COVID-19 at a Kentucky nursing home was caused by a single unvaccinated employee, according to a new study by the Center for Disease Control and Prevention, but residents and employees who were vaccinated were much better protected.
The outbreak was linked to dozens of infections in both employees and residents, including 22 residents and workers who had already been vaccinated. The virus was introduced from a single employee who was not vaccinated and symptomatic.
However, attack rates were three to four times higher among unvaccinated residents and employees than among those who were vaccinated, and 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 completely vaccinated, and 20 health professionals, in which four were vaccinated.
A vaccinated resident, who had previously been infected 300 days earlier, was re-infected during the outbreak and died. Two unvaccinated residents also died.
The low rate of advanced infections and the fact that most advanced infections were asymptomatic underscores the importance of vaccinating residents and nursing home staff.
The coronavirus is more likely to be introduced into a nursing home through an infected staff member who enters and leaves the facility regularly. At the Kentucky Nursing Home CDC examined, 90 percent of the 83 residents were vaccinated, but only half of the 116 employees were at the time of the March outbreak.
Low acceptance of vaccination among nursing home workers has been a national challenge and could increase the likelihood of COVID-19 being introduced and transmitted within a facility, the CDC said.
Vaccination of workers and residents “is critical to reducing the risk of the introduction, transmission, and severe outcomes of SARS-CoV-2” in nursing facilities, the CDC said.
The outbreak involved variant R.1 of the virus, which the CDC does not include as a variant of concern, but which contains multiple mutations in the peak protein that could make vaccines less effective.
The Pfizer-BioNTech vaccine showed an effectiveness of 66% of residents against infection and 75.9% of employees.
CDC acknowledged that both figures are lower than those reported in Israel’s national vaccination program. This could be due to reduced protection against variant R.1, but could also be due to a small sample size and the increased risk of exposure associated with an outbreak in a congregated environment.
However, CDC said vaccinated residents and staff were 87% less likely to present with symptomatic COVID-19 compared with those who were not vaccinated.
Meanwhile, a separate study published simultaneously on nursing homes in the Chicago area found that of the 627 people with COVID-19 infections in 75 homes, only 22 infections were found in vaccinated people and none occurred. secondary transmission associated with the facilities.
About two-thirds of these advanced infections were asymptomatic. However, two residents were hospitalized due to COVID-19 and one died.
CDC said the Chicago study shows that nursing homes still need to follow recommended infection and control practices and promote high immunization coverage among residents and staff members.