Nearly 20,000 fully vaccinated Massachusetts residents have now tested positive for COVID-19 and more than 130 of them have died, according to the latest state data on breakthrough cases published Tuesday.
The Department of Public Health has tracked a cumulative 19,443 confirmed COVID-19 infections among those fully vaccinated in the state to date and a total of 144 deaths.
The breakthrough cases represent just a small percentage -- about 0.43% -- of the more than 4.5 million people who have been vaccinated and the deaths an even smaller percentage -- just 0.003%
In the last week alone, 3,074 new breakthrough cases -- infections in people who have been vaccinated -- have been reported. Health officials said 651 of the new breakthrough cases resulted in hospitalization, or about 0.01% of all fully vaccinated individuals.
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Breakthrough infections again accounted for about 40% of all cases reported in Massachusetts last week.
The number of new breakthrough cases announced each Tuesday has climbed each week since DPH announced the initial batch of 7,737 breakthrough infections on July 31.
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Dr. Philip Landrigan, director of the Global Public Health Program at Boston College, told The Boston Globe last month that the rise in breakthrough cases “reflects the fact that the delta variant is loose in the population, and it reflects the fact that there’s a lot of virus circulating around.”
Experts also told the Globe the increase in breakthrough cases is attributable to diminishing immunity from the COVID-19 vaccines, emphasizing the need for booster shots in the coming months.
Tuesday's report pushed the state's cumulative confirmed COVID-19 caseload to 709,599 since the start of the pandemic and its death toll to 17,874.
Overall case numbers have been on the rise in Massachusetts and nationwide for weeks as the highly infectious delta variant spreads, including among those who are fully vaccinated, but health experts have repeatedly stressed that vaccinations reduce the risk of serious injury or death in the rare breakthrough cases.
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Tufts Medical Center Epidemiologist Dr. Shira Doron put the rare deaths among fully vaccinated people into context in a recent conversation with NBC10 Boston.
"We do need to put some of these numbers in a more realistic context just so people, you know, so people don't panic, so people make the right decisions based on the actual risk," Doron said.
She said that while breakthrough cases are concerning, they're not as concerning as the need for vaccinations worldwide.
"Most data, with some notable exceptions, suggest that effectiveness against the delta variant is maintained, with only negligible decrement compared to alpha," Doron said of the vaccines.