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Results released for antibody and COVID-19 testing of Boston residents

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Published by:

Public Health Commission

About 1 in 10 residents in this study have developed antibodies and approximately 1 in 40 currently asymptomatic individuals are positive for COVID-19 and potentially infectious. 

Mayor Martin J. Walsh, together with Massachusetts General Hospital (MGH), and the Boston Public Health Commission (BPHC), today announced the study to evaluate community exposure to COVID-19 through a representative sampling of asymptomatic Boston residents resulted in 9.9% testing positive for antibodies and 2.6% of currently asymptomatic individuals testing positive for COVID-19. In conclusion, approximately 1 in 10 residents in this study have developed antibodies and approximately 1 in 40 currently asymptomatic individuals are positive for COVID-19 and potentially infectious. 

"We can draw two preliminary conclusions from the results of this study," said Mayor Walsh. "First, that the actions we took early on in this pandemic made a real difference in slowing the spread and, second, that the majority of our population still have not been exposed to the virus. This underscores what we already know, that we have to move cautiously and stay focused on what got us this far. This can be done by a gradual, phased-in approach to reopening that includes clear health criteria and safety guidelines for each industry and depends on testing and hospital metrics reaching certain benchmarks, and continuing to move in the right direction." 

Mayor Walsh was joined by Boston Public Health Director Dr. Jennifer Lo (left) and physicians from Mass General Hospital for his COVID-19 update on Friday.

More than 5,000 residents living in East Boston, Roslindale or within the boundaries of zip codes 02121 and 02125 in Dorchester were invited to voluntarily participate in the study, with total outreach representing more than 55% people of color. Approximately 1,000 residents expressed interest in participating and 786 residents were deemed eligible. Of those, 750 residents enrolled in the study and received the required testing. Residents with symptoms or a previously positive COVID-19 test were disqualified from the study.

Baseline demographics of the 750 participants:

  • Median age is 42.4 years old
  • 61.6% are female, 38.3% male
  • 36.8% are from Roslindale, 25.1% are from East Boston, 23.2% are from 02125 in Dorchester and 14.9% are from 02121 in Dorchester
  • 62% are white, 18.7% are Black/African-American, 12% are Latinx/Hispanic, 2.3% are Asian/Pacific Islander and .13% are American Indian/Alaska Native. 1.6% preferred not to say and 1.6% are unknown. There were no significant differences in COVID-19 or antibody rates by race or ethnicity in this sample.

Prevalence of COVID-19 positivity in currently asymptomatic individuals ranged from 1.1% to 4.6%, while antibody positivity ranged from 6.3% to 13.3% by zip code.

  • East Boston: 1.1% tested positive for COVID-19, 13.3% tested positive for antibodies
  • Roslindale: 2.2% tested positive for COVID-19, 7.6% tested positive for antibodies
  • 02121 in Dorchester: 2.7% tested positive for COVID-19, 6.3% tested positive for antibodies
  • 02125 in Dorchester: 4.6% tested positive for COVID-19, 12.1% tested positive for antibodies

"Making sound decisions about safely reopening requires that we understand how extensively the virus has already spread in our community," said Peter L. Slavin, MD, president of Massachusetts General Hospital. "The testing that the teams from Boston and the MGH conducted shows that approximately 90 percent of the city's residents have not yet been exposed to the virus. We also know that COVID-19 will be with us for a while. It is vital therefore that we be thoughtful and careful about reopening, and that we continue to take actions - wearing masks, physical distancing, working from home when possible, limiting gatherings - that can prevent another surge of the disease."

Testing was conducted at three drive through testing sites in East Boston, Roslindale and Dorchester. Testing for COVID-19 virus is done by means of a swab of the nose and determines if you have the infection. Antibody testing is done by means of blood drawn through a finger prick and detects whether your blood has antibodies that are present when the body is responding to an infection, like COVID-19. Any resident who tested positive for the COVID-19 virus or the COVID-19 antibodies was provided with clear guidance and information on how to care for themselves and those around them.

This announcement builds on Mayor Walsh's commitment to increase access to testing for Boston residents, which will allow for better understanding of the spread and inform a path to recovery. Boston is currently offering testing in over 20 locations, including hospitals and community health centers. During April 30 and May 7 alone, Boston had a 30 percent increase in the amount of testing happening citywide. By the end of last week a total of 36,072 tests had been conducted.

On Monday, Mayor Walsh announced that the City's first round of universal testing for all unhoused individuals in Boston was completed. Over 2,200 homeless individuals were tested, with 743 testing positive for a 32% infection rate. In addition, Mayor Walsh is working on universal testing at city substance use residential programs.

Through the Boston Resiliency Fund, the City has dedicated $1.24 million to expand COVID-19 testing and conduct culturally appropriate outreach and education at 17 community health centers in Boston neighborhoods. A full map of testing sites is available here. The map includes contact information for the testing site and it is updated as new sites come online. Residents who are sick and want to be tested should call ahead to be pre-screened and schedule an appointment. Residents will not be charged for testing and residents will not be asked about immigration status. 

In addition, the City of Boston has made available weekly data on testing at the neighborhood level, with new reports including the number of people tested, and positive testing rates for each neighborhood. The latest data was shared on Thursday, May 7 and can be found here