COVID-19 outbreak at skilled nursing facility linked to unvaccinated worker
Researchers identified an unvaccinated, symptomatic health care worker as the index patient in a COVID-19 outbreak at a skilled nursing facility in Kentucky that totaled 46 cases, many of them among fully vaccinated residents and staff.
“Although COVID-19 [messenger RNA] vaccines demonstrated high efficacy in clinical trials, they were not 100% efficacious,” Alyson M. Cavanaugh, PhD, DPT, MPH, a CDC Epidemic Intelligence Service officer with the Kentucky Department for Public Health, and colleagues wrote in MMWR. “Thus, some infections postvaccination are expected.”
According to Cavanaugh and colleagues, there are limited data on how effective the vaccines are in skilled nursing facilities (SNFs) and against emerging variants. Their report was based on an investigation by the state and local health department into a COVID-19 outbreak in an SNF that involved a SARS-CoV-2 variant, R.1, that had not previously been identified in Kentucky.
The CDC does not consider R.1 a variant of concern or interest, although it does have some “mutations of importance,” Cavanaugh and colleagues said.
According to their report, the outbreak occurred after all residents and health care personnel (HCP) had been offered the Pfizer-BioNTech vaccine as part of a clinic taking place on Jan. 10, Jan. 31 and Feb. 21. According to the study, among 83 residents and 116 HCP, 75 (90.4%) and 61 (52.6%), respectively, received two vaccine doses.
Vaccine hesitancy has been widely reported among staff at long-term care facilities, and research published in MMWR earlier this year raised concerns about among workers at the facilities.
The Kentucky outbreak was identified during routine HCP antigen testing on March 1 — 8 days after the final vaccine event. Cavanaugh and colleagues identified the index case as an unvaccinated, symptomatic HCP who experienced symptoms a few days before the next patients.
During the outbreak, 26 residents and 20 HCP received positive SARS-CoV-2 test results, including 18 residents and four HCP who had received their second vaccine dose more than 14 days before the outbreak began.
Among those infected, three residents died, two of whom were unvaccinated. The researchers identified four possible reinfections one in a resident and three among HCP. Of these reinfections, only one HCP was vaccinated.
Further assessment of the outbreak revealed that unvaccinated residents and HCP had 3 and 4.1 times the risk for infection as vaccinated residents and HCP. Cavanaugh and colleagues calculated that the vaccine was 86.5% protective against symptomatic illness among residents and 87.1% protective among HCP.
“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,” they wrote.