Charts: Many Mass. residents aren’t stepping up to get their COVID-19 booster shots

A health care worker prepared Moderna COVID-19 vaccine booster shots.Toru Hanai/Bloomberg

Even as the Omicron subvariant BA.2 raises concerns that COVID-19 cases will rebound, many people in Massachusetts have not taken advantage of booster shots to shore up their waning immunity.

The Department of Public Health, in a report released Thursday, said that only about 55 percent of the state’s 5.3 million fully vaccinated people have gotten their boosters. DPH data shows that after the boosters were first authorized last year, Massachusetts residents rushed to get them in the fall and early winter, but the numbers have been tapering off.

A person is considered “fully vaccinated” if they’ve received two doses of the mRNA vaccines from Pfizer or Moderna, or if they’ve received one dose of the Johnson & Johnson vaccine. Everyone 12 and older who has been fully vaccinated should also receive a booster, according to the US Centers for Disease Control and Prevention.

People are eligible to get a booster shot five months after their second Pfizer or Moderna shot, or two months after their Johnson & Johnson shot.

“It is very important for people who are eligible to get boosted,” said Dr. Sabrina Assoumou, an assistant professor of medicine at Boston University School of Medicine and an attending physician in the section of Infectious Diseases at Boston Medical Center. “You need that booster to get to that higher level of protection.”

DPH data shows that older residents have been more likely to get boosters, including 77 percent of fully vaccinated people who are 75 and older. At the other end of the spectrum, only 29 percent of fully vaccinated 12- to 15-year-olds have gotten boosted. (Vaccines have been authorized for 5- to 11-year-olds but not boosters. No vaccines have been authorized for children under 5, although Moderna said Wednesday it would file an application for children between 6 months and 5 years).

The state’s booster rate among fully vaccinated residents is better than the national average of 45 percent, the DPH said.

But experts and officials said that a resurgence of cases and hospitalizations in the United Kingdom and other European countries underscores the need for increased vaccine and booster rates. Factors suspected of driving the trends in Europe include the lifting of pandemic restrictions, the waning of immunity from vaccinations and previous infections, and the arrival of the BA.2 subvariant, which is more contagious. Similar factors are at play in the United States, experts said. And recent data has shown BA.2 is on the rise nationally and in New England.

“What happens in Europe tends to foreshadow what happens here,” Assoumou said. “The best way to be ready for a possible increase in cases ... is to first get vaccinated and boosted.”

Assoumou said some people may not realize how crucial booster shots are, especially for the elderly and people with underlying health conditions. Other people may be hoping for protection from a prior infection, unaware that the CDC recommends they still receive a booster. Still others may struggle to find the time to get a shot or worry about missing work from its side effects.

“We need to get the word out there — and also make it easier to get vaccinated,” she said.

People may also be confused by certain public health messages, such as designating people who have not received booster shots as “fully vaccinated.” She said she expected the definition of “fully vaccinated” will eventually include the booster.

The Biden administration is reportedly pondering authorizing a second booster shot for people 65 and older, as BA.2 concerns swirl. Assoumou said that seemed like a “really hard sell — let’s get that first booster in.”

Dr. Paul Sax, clinical director of the Division of Infectious Diseases at Brigham and Women’s Hospital, said “data from multiple countries strongly support getting a third dose [a booster], in particular for optimal protection against all forms of Omicron, including BA.2.”

“This is particularly important for older people [anyone over 50] and those with multiple medical problems,” he said. “The good news — it’s safe and rapidly provides protection, so it’s not too late.”

The state Executive Office of Health and Human Services said in a statement that “Massachusetts is a national leader in vaccination rates” and residents “have ready access to vaccines, rapid tests, and therapeutics — all the resources needed to stay safe from severe illness. The administration will continue to work with the healthcare community and the federal government to monitor all of the latest developments.”