Mass. reports 3,741 new breakthrough cases this week

There have been another 46 deaths among vaccinated individuals.

There were over 600 fewer breakthrough cases of COVID-19 in vaccinated individuals this week compared to last, but thousands across Massachusetts are still reporting breakthrough infections. 

The state released updated data Tuesday on the number of COVID-19 cases, hospitalizations, and deaths among vaccinated individuals in Massachusetts. There have been a total of 40,464 breakthrough cases of COVID-19 as of Oct. 2, an increase of 3,741 from Sept. 25. Between Sept. 18 and Sept. 25, 4,378 breakthrough cases were reported, so 637 fewer breakthrough cases were reported this week, continuing a downward trend.

There were 4,633,805 people vaccinated as of Oct. 2, meaning 0.87% reported a breakthrough case of COVID-19. The rate has been steadily increasing — it was 0.23% on Aug. 7. 

Though this reflects the overall trend of how many vaccinated people are reporting cases, it’s easier to understand on a week-by-week level. So, for example, how many of the new cases reported this week were breakthrough cases.


Between Sept. 26 and Oct. 2, 8,912 people tested positive for COVID-19 (over 1,500 less than the week before), and 3,741 breakthrough cases were reported. Meaning 42% of COVID-19 cases in that period were breakthrough cases. The week before that, 41.9% of COVID-19 cases were breakthrough infections, so it’s remained pretty consistent for a couple of weeks.

Hospitalizations and deaths are also increasing but at a much lower rate. Tuesday’s data showed a total of 1,280 hospitalizations and 300 deaths, an increase of 125 and 46 respectively from Sept. 25. Out of vaccinated individuals, 0.03% have been hospitalized and 0.006% have died. According to the data, 3.16% of breakthrough cases resulted in hospitalization and 0.74% resulted in death.

As of Sept. 25, the median age of fully vaccinated individuals in Massachusetts who died from COVID-19 was 82.3. Additionally, 71 percent of breakthrough deaths were reportedly individuals with underlying conditions that made them more vulnerable to the disease. 

Nearly six out of 10 of the state’s vaccinated individuals who were hospitalized with COVID-19 also were reported to have underlying conditions.

Officials note that these numbers may be revised as case investigations continue.

Last month, Massachusetts made COVID-19 booster shots available to those who had gotten the Pfizer vaccine and were either over the age of 65, had an underlying health condition, or face increased risk of getting the disease because of their job.


Broad COVID-19 death and hospitalization data also show the highest rates among residents 80-years-old and older. Between Sept. 12 and 29, 60.7% of hospitalizations were among those over 80 and 35.1% were among those aged 70 to 79. By comparison, 5.9% of 20 to 29-year-olds with COVID-19 were hospitalized during that period. The story with deaths is similar: more young people test positive, but more elderly residents who test positive die.

Experts continue to emphasize the importance of the vaccine because it will reduce the likelihood of serious illness and death. 

“It’s likely that everybody will probably get infected with COVID-19 [at some point] because it’s an endemic respiratory virus,” Amesh Adalja, a doctor and infectious disease specialist at Johns Hopkins Center for Health Security, told Roll Call. “The goal is to make sure that at that time, that infection occurs after you’ve been vaccinated so it’s mild.”

Emory University School of Medicine professor Carlos del Rio told Roll Call why vaccines remain important, especially in areas of high community transmission.

“If I’m in a little bit of rain and I have an umbrella, I don’t get wet. But if I’m in a hurricane, I’m going to get wet despite wearing an umbrella. That doesn’t mean you can say, all of a sudden, umbrellas don’t work very well,” he said. “It’s a hurricane.”


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