More than two years into the pandemic, local health experts are closely watching an increase in COVID-19 cases in Massachusetts driven by a more transmissible subvariant of the virus, while rates of new vaccinations and booster shots have leveled off.
Amid the rise in cases locally, specialists encouraged vaccinated people to get their booster shots to help reduce the chance of severe infection and to ease pressure on an already beleaguered health system.
Dr. Paul Sax, clinical director of the Division of Infectious Diseases at Brigham and Women’s Hospital, said a third shot of a two-dose vaccine is critical for reducing the risk of hospitalization and death.
“Getting that third dose should be a top priority for everyone who has had two,” Sax said.
Sax and other health officials are watching Europe, including the United Kingdom, which hit a record number of nearly 5 million cases Sunday due largely to the BA.2 subvariant, according to the Associated Press.
On Friday, state health officials reported about 1,440 new confirmed cases, along with 10 new confirmed deaths due to the coronavirus. More than 1.5 million cases have been reported in the state, and the virus has killed 19,006 people since the pandemic began in early 2020.
In Massachusetts, state data indicated a 7-day average of about 970 new cases as of March 30, up from about 600 cases earlier in the month.
“We are expecting an increase in cases; all signs point to a new wave. But that alone isn’t cause for concern,” said Matthew Fox, a Boston University School of Public Health professor of epidemiology and global health. “What we are looking to see is how much of an increase [we are] going to see. The hope is this will be a shorter and smaller wave than previous ones.”
Nearly three quarters of new coronavirus cases reported in New England from March 20 to March 26 are of the more transmissible Omicron subvariant BA.2, according to US Centers for Disease Control and Prevention data, up from more than half the previous week.
Dr. David Hamer, a physician at Boston Medical Center and a professor at Boston University’s School of Public Health and School of Medicine, said people need to keep up their guard.
“While Omicron and BA.2 appear to cause less severe disease, there are still unvaccinated people in our midst and they are at risk for becoming quite ill, plus we need to urge social behaviors that reduce risk of transmission,” Hamer said.
In February, when case counts were plummeting following the Omicron surge, state public health officials dropped a recommendation that healthy and fully vaccinated people wear masks in indoor public places, and eliminated a requirement for mask-wearing in schools.
Andrew Lover, a professor of epidemiology at the School of Public Health and Health Sciences at the University of Massachusetts Amherst, said state waste-water data will be an important indicator of the virus’ presence.
Waste-water data collected from more than 40 communities, including Boston, most recently showed an increase in coronavirus levels around mid-February, according to data reported by the Massachusetts Water Resource Authority.
Given the trends in Europe and slow increase in cases here, Lover anticipated the state will see a wave of new infections.
“It may be harder for us to see a new BA.2 wave coming with more limited availability of testing across the state, so the Boston metro waste water will be our best early-warning signal,” Lover said in an e-mail.
Fox said, in an e-mail, that people should not panic because of an increase in cases. He noted there is access to vaccines and better treatment for COVID-19, and officials are better able to respond to increases in new infections.
People “should be prepared to make some changes to our lives, should that be necessary (meaning should it be more severe than we hope),” Fox said. “That might mean bringing back masking for the duration of the wave and reducing our contacts.”
While about 77 percent of Massachusetts residents are fully vaccinated, according to state data, rates of new vaccinations have leveled off. And only 55 percent of the state’s fully vaccinated residents have received booster shots since the CDC authorized them in the fall.
Those trends are mirrored in national vaccination data, which indicates vaccinations have plateaued, despite only two-thirds of the US population receiving either both doses of the two-shot Pfizer or Moderna vaccine, or the single-dose Johnson & Johnson vaccine, according to the CDC.
Hamer said in an e-mail that he is strongly encouraging people who have not yet received their booster to get the shot, and that the state should develop strategies to facilitate access to the booster.
“Increasing ease of access and communication about the importance of the booster, especially for presenting severe disease and hospitalization, is important,” Hamer said.
Sax said people who received the J&J vaccine should still get two doses of the vaccine manufactured by Moderna or Pfizer.
“Getting people that third dose ... is really critical. The words ‘fully vaccinated’ are misleading — with omicron, this means 3 doses, not two,” Sax said.
In an online post published Friday, Sax raised concerns that the Omicron surge has encouraged much of the country to “move on” from the pandemic, end health measures like vaccine mandates, and leave masks at home.
But Omicron led to a “staggering number” of hospitalizations and deaths, Sax wrote, and hospitals used ICU beds for COVID patients and took steps like delaying non-essential surgeries and disrupting patient care to help respond to the crisis.
“We can hope that case numbers will be lower during the BA.2 Omicron surge — and they might be — but we can’t count on it,” Sax wrote.
John Hilliard can be reached at email@example.com.