An unvaccinated worker at a Kentucky nursing home set off a coronavirus outbreak, killing 3 residents

• The CDC reported this week on a March COVID-19 outbreak at a Kentucky nursing home that killed 3.
• Investigators determined that the outbreak was caused by an unvaccinated health worker.
• All the residents and workers at the facility had been offered a vaccine.

An unvaccinated health worker started a coronavirus outbreak at a Kentucky nursing home in March, which led to three residents dying, a Centers for Disease Control and Prevention report released on Wednesday found.

The CDC looked into the March outbreak to evaluate the effectiveness of the Pfizer-BioNTech two-shot vaccine in a skilled nursing facility setting. It found that most of the fully-vaccinated people in the facility who tested positive ultimately avoided hospitalization.

When the outbreak was first identified through regular testing on March 1, all residents and healthcare personnel at the facility had been offered the Pfizer vaccine, though some declined or were not fully vaccinated yet, the report's authors said.

Ninety percent of the residents were fully vaccinated - meaning they received their second dose more than 14 days prior - compared to 52.6% of the health care workers at the facility.

An unvaccinated, symptomatic worker

The outbreak was traced to an unvaccinated, symptomatic healthcare worker, who then spread the virus to 46 residents and workers at the facility, the CDC report said.

Of the 26 residents who tested positive, 18 had been fully vaccinated, the report said. Four of the 20 health care workers who tested positive were also fully vaccinated.

Three residents died in the outbreak, one of whom was fully vaccinated, the CDC said.

One of the residents who died had contracted COVID-19 about 10 months prior, the report said. It is not clear if this resident had been vaccinated.

The investigators found that the vaccine proved mostly effective at stopping symptomatic COVID-19 cases and curbing hospitalizations. More than 86% of the fully-vaccinated residents who tested positive for COVID-19 were asymptomatic, compared to more than 87% of health care workers.

More than 94% of fully-vaccinated residents who tested positive avoided going to the hospital, and no healthcare workers who tested positive had to be hospitalized.

The importance of getting vaccinated

The authors of the CDC report said the case "underscores the importance" that everyone get vaccinated, "including those who have recovered from COVID-19."

The authors added that low vaccination rates among healthcare personnel could lead to more outbreaks at nursing facilities in the future, pointing out that just 37.5% of health workers in long-term care facilities had received at least one dose of a COVID-19 vaccine as of mid-January 2021.

While the vaccination rate among health workers at the Kentucky facility surpassed this rate at the time, it still led to a serious outbreak.

In order to protect nursing facility residents, the authors said "it is imperative" that health workers and nursing-home residents "be vaccinated."

Vaccination doesn't fully protect a person from getting COVID-19, but it drastically reduces the chance of getting a serious infection, the CDC has said. Of the 75 million Americans that were vaccinated as of April 13, there were 5,800 "breakthrough cases" and 74 deaths, the agency said last week.

A CDC report released last month also found that vaccinations were 90% effective at preventing infection among healthcare and frontline workers, meaning they were 90% less likely to catch COVID-19 despite their constant exposure to the virus on the job.