Boston is rolling out a program to test 1,000 residents for coronavirus antibodies in their blood as part of a study conducted with Massachusetts General Hospital to gauge what percentage of people may have been exposed without developing symptoms, Mayor Martin J. Walsh said Sunday.
Walsh said the tests will focus on East Boston, Roslindale, and parts of Dorchester ― which are among the city’s hard-hit neighborhoods. Researchers have already begun recruiting participants for the effort, the largest of its kind to date in Massachusetts.
Walsh said he hopes the tests will provide "a better understanding of the true prevalence of COVID-19 in our community.” Dr. Peter L. Slavin, president of Massachusetts General Hospital, said the results of the testing initiative will provide important intelligence in what he described as a “war” against the virus.
The effort comes as public officials around the state are trying to get a grip on the scale of the crisis ― and what it might take to reopen businesses.
In Somerville, city officials on Monday are set to announce a plan to test some residents for active cases of the virus, even if they are asymptomatic. And the state is ramping up an ambitious effort to track down people who have been in contact with known COVID-19 patients in an attempt to prevent further spread.
The latest plans were announced as the state said it had detected 1,590 new cases of coronavirus across Massachusetts, bringing the total to 54,938. The state Department of Public Health also reported 169 additional deaths, for a statewide toll of 2,899.
The number of new cases was the smallest in nearly two weeks, though the number of new tests reported also dipped, to 9,255, and state officials caution against attaching excessive significance to any single day total because of variations in testing.
The numbers on Sunday continued to show that while the pandemic is affecting people of all ages, it has been particularly devastating to elderly people and those in nursing homes.
A total of 1,632 people who have died with COVID-19 lived or worked in long-term-care facilities in Massachusetts ― about 56 percent of all such deaths. More than 10,000 residents and workers at those facilities have tested positive for the disease, while 303 long-term-care facilities have at least one case of the coronavirus.
In Boston, where there had been 8,159 confirmed coronavirus cases and 302 deaths by Sunday, Walsh has cited the need for universal testing as a prerequisite for allowing the local economy to start to return to normal.
Antibody testing, which is different from conventional tests for active cases of the virus, looks for the presence of antibodies, which are created by the immune system in response to the virus and can remain after recovery.
It is not yet known whether people who have coronavirus antibodies are immune from reinfection, and some scientists have raised concerns about the reliability of antibody tests developed for the new virus.
However, public health authorities hope testing programs like the one in Boston can help them plot their response, because the results may give an indication of how many people have had COVID-19 with few or no symptoms.
“The more we can expand our testing, the more we can learn how to use our medical resources more efficiently, and how we need to focus our current efforts to contain the virus,” the mayor said in a statement Sunday.
Mass. General said the antibody study in Boston is the largest of its kind in Massachusetts, though others are likely to follow soon.
A smaller Massachusetts study earlier this month in Chelsea, also carried out by Mass. General researchers, found that nearly a third of 200 residents tested on the street had antibodies linked to COVID-19.
Boston residents in the target areas are being selected at random, and participation is voluntary. Participants will be tested both for active cases of COVID-19 and antibodies.
Residents will not be charged for the testing, according to the city. The testing is expected to be complete by Friday.
Dr. Michael Mina, a professor of epidemiology at the Harvard T.H. Chan School of Public Health, said he was skeptical about what can be learned from an examination that includes only limited areas.
“A one-time snapshot will give some needed information … at least let us know in these communities how hard have they been hit,” he said. “But it does leave us in the position afterward where we don’t know how to interpret that, other than there has been a lot of transmission in these low-income and impoverished areas.”
He said such tests, given their scope, will not actually prove these communities are a hot spot.
“I worry about a stigma being associated with these places,” Mina said.
The city says it selected the neighborhoods for the study by looking at many factors.
East Boston has seen less testing per capita than many other neighborhoods, for instance. The northern parts of Dorchester in the study have a large, diverse population and many cases of coronavirus. And city officials said they chose Roslindale because it is geographically away from the other neighborhoods and also has a lower rate of testing than other areas.
The city has not yet decided whether to expand the program to other areas.
“A growing body of evidence suggests that many people who have been infected with COVID-19 are asymptomatic, but we don’t yet know how prevalent the disease is in our city, in our communities, and in our society," Slavin said in a statement.
City Councilor Lydia Edwards, whose district includes East Boston, said she hopes the study will help head off a second wave of infections. She said the results could “enhance the awareness that we need in all our communities: You are spreading this disease even if you don’t have any symptoms.”
In Somerville, Mayor Joseph A. Curtatone on Monday is set to announce a new system for testing and tracking cases, including through the use of remote digital health monitoring devices for people with the virus who are not hospitalized. The city has been working with the Cambridge Health Alliance to offer tests to all residents, regardless of whether they are CHA patients.
Residents who are interested in tests should call CHA to see if one is medically warranted, Curtatone said. But he said his goal is to make it available to people without symptoms so his administration can understand how the outbreak is playing out in his community ― especially among low-income and vulnerable populations.
John Hilliard of the Globe staff contributed to this report, which also includes material from The Associated Press.