Harbor Hill Center in Belfast is under investigation after seven people tested positive for the coronavirus. Credit: Abigail Curtis / BDN

A coronavirus outbreak at Harbor Hill Center in Belfast is under investigation after seven people tested positive for the virus, the Maine Center of Disease Control announced Thursday.

Four residents of the center’s nursing home and three staff members have been infected after the outbreak started on Jan. 22, according to Dr. Richard Feifer, the chief medical officer for Genesis HealthCare, which runs the facility.

Of those who tested positive, some had not been vaccinated or had only received the first dose of the vaccine, he said.

“Vaccination is the critical third leg of the stool, along with personal protective equipment and testing, in stemming COVID-19 spread in nursing homes and protecting residents and healthcare workers. This is unquestionably the biggest vaccination effort ever undertaken and will help prevent further tragedies, especially in this vulnerable population,” Feifer said.

Harbor Hill, which also has an assisted living unit, has completed three planned vaccine clinics in partnership with CVS. Those took place on Dec. 22, Jan. 12 and Feb. 2 and were available to all staff and residents, according to the chief medical officer.

So far, approximately 90 percent of residents and 63 percent of staff members have received the COVID vaccine. That’s more than the national median of nearly 80 percent of residents and less than 40 percent of staff members who have received one or more doses, according to the Centers for Disease Control and Prevention.

“As a reminder, the Pfizer vaccine was deemed to be approximately 95 percent effective and requires two to three weeks to reach maximum efficacy,” Feifer said.

As of Friday, Waldo County has recorded 529 coronavirus cases and 18 deaths since the pandemic reached Maine in March 2020.