FILE PHOTO: COVID-19 vaccines

New data from the State Department of Public Health said no fewer than 4,000 fully vaccinated people in Massachusetts, US, have tested positive for COVID-19.

The number of breakthrough cases in the state has accounted for approximately one in 1,000 vaccinated people.

The state Department of Public Health said as of June 12, there were 3,791 coronavirus cases among the more than 3.7 million fully vaccinated individuals in Massachusetts.

According to the Centers for Disease Control and Prevention, large-scale clinical studies have found that COVID-19 vaccination prevented most people from getting the virus.

Still, no vaccine is 100% effective at preventing the disease and there will be “a small percentage of fully vaccinated people who still get sick, are hospitalized, or die from COVID-19.”

“We’re learning that many of the breakthrough infections are asymptomatic or they’re very mild and brief in duration,” said Boston University infectious diseases specialist Davidson Hamer, according to the Boston Herald.

“The viral load is not very high.”

“Breakthroughs are expected, and we need to better understand who’s at risk and whether people who have a breakthrough can transmit the virus to others,” he continued.

“In some cases, they’ll be shedding such low levels of the virus and won’t be transmitting to others.”

“Testing to identify current infection remains critical to control of COVID-19,” a DPH spokeswoman said.

“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.”

A new study from the CDC showed that Pfizer and Moderna are about 90% effective against infection two weeks after the last dose has passed while the one-dose Johnson & Johnson vaccine is about 72% effective against moderate to severe disease.