More than 27,700 fully vaccinated Massachusetts residents have now tested positive for COVID-19 and more than 190 of them have died, according to the latest state data on breakthrough cases published Tuesday.
The Department of Public Health has tracked a cumulative 27,777 confirmed COVID-19 infections among those fully vaccinated in the state to date and a total of 194 deaths.
The breakthrough cases represent just a small percentage -- about 0.61% -- of the more than 4.7 million people who have been vaccinated and the deaths an even smaller percentage -- just 0.004%
In the last week alone, 3,919 new breakthrough cases -- infections in people who have been vaccinated -- have been reported. Health officials said 61 of the new breakthrough cases resulted in hospitalization, or about 0.02% 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.
Dr. Philip Landrigan, director of the Global Public Health Program at Boston College, told The Boston Globe 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 731,564 since the start of the pandemic and its death toll to 18,015.
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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Dr. Daniel Kuritzkes, chief of Brigham and Women’s Hospital's infectious diseases division, put the rare cases among fully vaccinated people into context in a recent conversation with NBC10 Boston.
"Although the numbers of breakthrough cases appear daunting at first glance, it’s important to keep them in perspective—people who are vaccinated are still are far lower risk of becoming infected and needing to be hospitalized," Kuritzkes said.
The data continue to show the high effectiveness of the vaccines, even now that Delta accounts for essentially 100% of cases, Kuritzkes said, particularly when it comes t reducing the risk of hospitalization and death.
"Although any deaths from COVID-19 are tragic, the number of deaths from COVID-19 that have occurred among vaccinated people are a tiny fraction of all COVID deaths, and people who have been vaccinated are 11 times less likely to die from COVID than those who are unvaccinated," Kuritzkes said.
