Ninety-seven percent of vaccinated people in Massachusetts who became sick with COVID-19 in breakthrough cases did not become severely ill, according to a new review by state health officials.
Furthermore, deaths of vaccinated people were rare in Massachusetts breakthrough cases, especially among young people, officials from the Department of Public Health said Monday.
The state has seen no one under 30 years old die from a COVID-19 infection if they've been vaccinated, and 99.9% of breakthrough cases in fully vaccinated people under 60 did not end in death either. For people over 60, 97% of such cases didn't end in death, according to the study.
And booster shots appear to provide far more protection against breakthrough cases than getting two shots, the study found: boosted residents were 31 times less likely to become infected than unvaccinated residents, whereas people with only two does of Moderna and Pfizer vaccines or one dose of Johnson & Johnson's were five times less likely to become infected than unvaccinated residents.
Health and Human Services Secretary Marylou Sudders called the data clear and urged state residents to get vaccinated and their booster shot.
"This review shows that fully vaccinated people in Massachusetts have near-universal protection from severe illness and death and that boosters are demonstrating even stronger protection from COVID," she said in a statement, calling immunization "the best gift of protection for yourself and your loved ones."
She and acting Department of Public Health Commissioner Margret Cooke both stressed that vaccines remain important in light of the emerging omicron variant of COVID-19, which is thought to be more infectious than the currently predominant delta variant.
Gov. Charlie Baker took note of the study and its findings, calling "clear" that "getting fully vaccinated and boosted is the best way to protect yourself, your community and your loved ones against hospitalization or death."
The data on Massachusetts breakthrough cases run from various points in 2020 and either Nov. 28, 2021, or Dec. 4, 2021, depending on the information. Dec. 4 is the day the first case of the omicron variant was detected in Massachusetts.
NBC10 Boston has reached out to health officials on whether they think that some of the percentages would change if and when omicron becomes more prevalent in the population.
More on COVID in Mass.
The most recent data from the U.S. Centers for Disease Control and Prevention also show that vaccines help prevent COVID infection.
Toward the end of November, unvaccinated people had a 0.45% rate of COVID infections, compared to 0.13% for people considered fully vaccinated and 0.05% for people with booster shots. There was a starker difference in death rates in the most recent CDC data, with unvaccinated people orders of magnitude more likely to die from COVID than unvaccinated people.