COVID breakthrough infections soar in Massachusetts

Still represent tiny fraction of vaccinated total

BOSTON — Since late July, the state Department of Public Health reports breakthrough COVID-19 infections -- that is, infections that develop in those fully vaccinated -- have risen to a cumulative total of just under 10,000 Massachusetts residents.

In just released data, DPH found 9,969 cumulative breakthrough cases. That’s up from 7,737 cases on July 31 and 6,373 cases the week before that.

MORE: 100 breakthrough cases in Massachusetts have ended in death

Hospitalizations jumped from 395 patients to 445 between July 31 and August 7. And total deaths due to breakthrough cases rose by six last week for a cumulative total of 106.

Last week, DPH reported the median age of the deceased was 82.5 years old with most, 73 percent, suffering some sort of comorbidity.

“The vaccines are 95 percent effective, not a hundred percent,” said William Schaffner, MD, an infectious disease and vaccine specialist at Vanderbilt University in Nashville, Tennessee. “We know that many of those people, older already, probably had serious underlying illnesses. Then if COVID hits you on top of that -- that may be sufficient to graduate you to heaven.”

Schaffner said he does not believe, given the median age, the data from Massachusetts suggests an early sign of waning vaccine immunity.

“At the moment as we look at the national data, we do not see a substantial uptick in people who are older or immunocompromised getting very sick and requiring hospitalization,” Schaffner said. “If we saw that uptick, then we would have to think much more seriously about giving people another dose, a booster dose.”

To some extent, the rise in breakthrough cases can be explained by the proportional rise in the number of people vaccinated, said Matthew Ferrari, PhD, Director of The Center for Infectious Disease Dynamics at Pennsylvania State University.

“Proportionally this is a very, very small number amongst all the many millions of people that have been vaccinated,” Ferrari said. “But, of course, as an individual number, one or a hundred deaths, is concerning and frightening.”

Ferrari said it’s great to have vaccines that are 90 to 95 percent effective. But there’s a flipside everyone has to remember when it comes to those breakthrough infections:

“Five or ten percent of millions of people that have been vaccinated is still a demonstrably large number of people,” he said.

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