Mass. houses of worship can reopen under new guidelines, and a new CDC study shows why caution is needed

David Rossini with Bostonian Cleaning and Restoration of Braintree cleaned aisle at St Gregory's Church in Dorchester.David L. Ryan/Globe Staff

A new study from the US Centers for Disease Control and Prevention examines a coronavirus outbreak at an Arkansas church, highlighting the risks as Massachusetts allows churches to begin reopening.

The study found that among 92 attendees at a rural Arkansas church from March 6 to March 11, 35 people developed laboratory-confirmed COVID-19, the disease caused by the novel coronavirus. Three of the people died. An additional 25 cases spread into community, causing one death, the CDC found.

“This outbreak highlights the potential for widespread transmission of SARS-CoV-2, the virus that causes COVID-19, both at group gatherings during church events and within the broader community,” the CDC said in a Morbidity and Mortality Weekly Report issued Tuesday.

“High transmission rates of of SARS-CoV-2 have been reported from hospitals, long-term care facilities, family gatherings, a choir practice, and, in this report, church events. Faith-based organizations that are operating or planning to resume in-person operations, including regular services, funerals, or other events, should be aware of the potential for high rates of transmission,” the report said.

The state’s reopening plan, issued Monday, allows houses of worship to reopen immediately, but with a host of restrictions intended to prevent outbreaks. Those include limiting occupancy of buildings to 40 percent, requiring people inside to sit 6 feet apart if they’re not in the same family, requiring cleanings between services, requiring people to wear masks, and banning pre- or post-service gatherings such as coffee hours.

The state suggests that communal rituals such as taking communion or handshaking be modified. If possible, the state also suggests, services should be held outdoors.

Joseph Allen, a professor of exposure assessment science at the Harvard T.H. Chan School of Public Health, said, "We should be mindful and be wary of large gatherings of people in any context.”

He said such gatherings increase a person’s frequency and duration of contacts with other people and “you’re more likely to run into someone who has [the virus] in a larger group.”

He said it’s harder to maintain physical distancing from people and noted the research on choirs infecting large numbers of people.

“The question is what kind of controls are in place and how well are they managing it?” he said.

He suggested a number of measures similar to those outlined in the state guidelines, including limiting the number of people in the building, maintaining space between people, choreographing people’s entry and exit, and cutting back on activities that bring people together such as handshaking or touching common objects. He also said buildings’ ventilation and air filtration should be examined.

“I think it can be done safely ... if it’s managed right," he said.