CDC: Vaccines Helped Curb Impact of Nursing Home COVID Outbreak Set Off by Unvaccinated Worker

Despite a 90.4% resident vaccination rate, a nursing home in Kentucky suffered a COVID-19 outbreak that resulted in 44 resident infections and three deaths after an unvaccinated worker contracted and spread the virus, the Centers for Disease Control & Prevention (CDC) determined in a new report released Wednesday.

Despite the fact that the outbreak was caused by a viral variant not yet seen in the region, vaccinated residents and staff were 87% less likely to experience symptoms than their unvaccinated peers. The incident emphasizes the need for all skilled nursing facility residents and health care professionals (HCP) to receive the shots, the authors of the CDC’s most recent Morbidity and Mortality Weekly Report concluded.

“Vaccination of SNF residents and HCP is essential to reduce the risk for symptomatic COVID-19, as is continued focus on infection prevention and control practices,” the authors wrote.


The unnamed Bluegrass State facility had completed the last of three on-site Pfizer-BioNTech vaccine clinics on February 21, with uptake rates of 90.4% for residents and 52.6% for staff. The outbreak, which was first detected on March 1, was traced back to a single unvaccinated worker who had become infected with an “R.1 lineage variant” of the novel coronavirus, according to the report authors.

Of the three resident deaths that resulted from the outbreak, two had not received the vaccines; two vaccinated residents were hospitalized as compared to four who had not received the shots. Of the 22 unvaccinated residents who contracted COVID-19, 20 had symptoms, compared to just eight of the 22 vaccinated residents who tested positive.

Among health care workers, 16 unvaccinated staffers were infected, 15 of whom experienced symptoms; four vaccinated workers tested positive, and two had symptoms.


The team also found four potential repeat infections — one resident and three workers — all of whom were symptomatic.

“The risk for poor outcomes among unvaccinated SNF residents is highlighted by the hospitalization of four of the six unvaccinated, infected residents, and two subsequent deaths, including in one previously infected resident,” the researchers wrote in the MMWR. “This underscores the importance of the Advisory Committee on Immunization Practices’ recommendation that all persons, including those who have recovered from COVID-19, be vaccinated.”

Such cases are not necessarily surprising on their own, the researchers noted.

“Although COVID-19 mRNA vaccines demonstrated high efficacy in clinical trials, they were not 100% efficacious,” they wrote. “Thus, some infections post-vaccination are expected.”

Concerns about slower acceptance of COVID-19 vaccines among workers as compared to residents emerged early in the federal government’s vaccine rollout in nursing homes and other long-term care settings; the CDC report notes that the 52.6% vaccination rate at the Kentucky facility exceeded the national average of 37.5% clocked through early January.

“To protect SNF residents, it is imperative that HCP, as well as SNF residents, be vaccinated,” the authors wrote. “A continued emphasis on strategies for prevention of disease transmission, even among vaccinated populations, is also critical. Timely implementation of infection control strategies after outbreak identification likely contributed to the rapid decline in new cases during the second week of the outbreak.”

The specific R.1 strain is not one of the CDC’s “variants of concern,” according to the report, but the team did stress that such new forms of the coronavirus could present problems in the future.

“Although vaccination was associated with decreased likelihood of infection and symptomatic illness, 25.4% of vaccinated residents and 7.1% of vaccinated HCP were infected, supporting concerns about potential reduced protective immunity to R.1,” the authors wrote. “In addition, four possible reinfections were identified, providing some evidence of limited or waning natural immunity to this variant.”