Nearly 4,000 MA Residents Got Coronavirus After Vaccinations

MASSACHUSETTS — About one out of every 1,000 Massachusetts residents who have been fully vaccinated against the coronavirus have tested positive for COVID-19 after they received their shots.

There were 3,791 of the so-called breakthrough cases as of June 12, according to the Massachusetts Department of Public Health, up 4.1 percent from 3,641 one week earlier. Health officials say there are likely more breakthrough cases than those that have been reported, as people who contract COVID-19 after being fully vaccinated rarely show symptoms.

The department echoed a call from the Centers for Disease Control and Prevention for vaccinated people to get tested, even if they have no symptoms, so researchers can track new mutations of COVID-19.

"Testing to identify current infection remains critical to control of COVID-19," a spokeswoman for the Department of Public Health said in a statement to News 10 Boston, which first reported this story. "People with current infection can spread the virus to others and isolation of cases and identification of close contacts (individuals who may have been exposed) is a foundation of public health response."

Nationally, the CDC stopped tracking breakthrough cases last month unless the patient ended up in the hospital. There were 10, 262 breakthrough cases in the U.S. as of April 30, when 101 million Americans had been fully vaccinated.