Breakthrough case review finds 97% of COVID-19 cases in vaccinated individuals don’t result in severe illness

BOSTON (December 20, 2021) – Today the Massachusetts Department of Public Health released a review of breakthrough COVID-19 cases in vaccinated Massachusetts residents and found nearly 97% of all breakthrough cases in the Commonwealth have not resulted in hospitalization or death. Additionally, thereview found unvaccinated residents are five times more likely to become infected than fully vaccinated residents (two doses of the Moderna or Pfizer vaccine or one dose of Johnson & Johnson) and unvaccinated residents are 31 times more likely to become infected than fully vaccinated residents who have received a booster.

The review also found that 99.9% of breakthrough cases among fully vaccinated people under the age of 60 did not result in death. Among the breakthrough cases for residents over the age of 60, 97% did not result in death. No deaths have been reported in breakthrough cases among those under age 30.

“The data are clear. 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,” said Health and Human Services Secretary Marylou Sudders. “Amid the season of gathering indoors and the emerging Omicron variant, the time to get vaccinated and boosted is now. It is the best gift of protection for yourself and your loved ones.”

“Vaccination continues to be the most effective tool we have against Omicron and all COVID-19 variants,” said Acting DPH Commissioner Margret Cooke. “The data indicates that fully vaccinated and boosted individuals are well protected from severe outcomes of COVID-19, including hospitalization and death, and the Department of Public Health strongly urges all residents to get vaccinated and, when appropriate, get a booster.”