One hundred people who had been fully vaccinated against the coronavirus died from the disease in Massachusetts by the end of July, according to the state Department of Public Health.
In about three-quarter of the breakthrough cases, the patients reported having underlying conditions, the department said. The median age of those who died was 82.5 years.
The deaths represent a tiny fraction -- about 0.002 percent -- of all fully vaccinated individuals in the state, according to state health officials.
"Breakthrough cases in Massachusetts are incredibly low, and those hospitalized or who have died are even lower," department officials said in a written statement.
"All available data continue to support that all three vaccines used in the US are highly protective against severe disease and death from all known variants of COVID-19. The best way to protect yourself and your loved ones is to get vaccinated," the statement added.
The department also reported 395 breakthrough hospitalizations in the state.