Nearly 4,000 people in Massachusetts have tested positive for COVID-19 after being fully vaccinated, according to recent data from the state’s Department of Public Health.
The number of breakthrough cases in the state has been infrequent so far — accounting for approximately one in 1,000 vaccinated people, Fox News reports. There were 3,791 COVID-19 cases among the more than 3.7 million fully vaccinated individuals in Massachusetts as of June 12, reports said.
The Centers for Disease Control and Prevention said clinical studies have found that COVID-19 vaccinations prevented most people from getting the virus, but no vaccine is 100% effective at preventing the disease — there will be “a small percentage of fully vaccinated people who still get sick, are hospitalized, or die from COVID-19,” the agency said.
“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 to the Boston Herald. “The viral load is not very high.”
Hamer continued: “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. In some cases, they’ll be shedding such low levels of the virus and won’t be transmitting to others.”
A recent 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, Fox News reports.
“Testing to identify current infection remains critical to control of COVID-19,” a DPH spokeswoman told Boston Herald. “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.”
Health officials also warned about the contagious Delta variant, seen in areas in the U.S. As of Monday, more than 150 million people in the U.S. have been fully vaccinated, according to the CDC.