Genesis Community Church, outside of Boston, thought it was taking all the right safety precautions for its Christmas services: requiring an R.S.V.P. in case contact tracing was needed, limiting capacity and requiring masks.
But it was not enough. More than 40 people have tested positive for the coronavirus in cases that are believed to be connected to those gatherings.
The house of worship in Woburn, Mass., hosted a total of four Christmas celebrations on Dec. 23 and Dec. 24. Its lead pastor, Michael Davis, who declined to be interviewed, said in a series of emails that those who wanted to attend were required to essentially make reservations.
That allowed the church “to do accurate and complete contact tracing of everyone who was in the building,” Mr. Davis said. “The average attendance at each gathering was 105 per service, which is 35 percent of our building occupancy.”
But, he said, he knows of at least 44 people who were at those services who have tested positive. Tara Vocino, 32, a local photographer, is one of them. She said that she was tested on Dec. 29 and received her positive result two days later.
“It feels like there has been a knife in my mouth, and I’ve lost all sense of taste and smell,” Ms. Vocino said, adding that she feels so exhausted that she has been sleeping “about 16 hours a day.”
She said that she was at one of the services on Dec. 23, was in the front row at the church and was wearing a mask.
“When I saw there was the outbreak, I went out and got tested,” she added.
Ms. Vocino, who lives with her parents and suffers from asthma, said, “I’ve been in one room for the last couple of days, and I use a separate bathroom.”
Mr. Davis said that he has also tested positive but is “almost back to full health.”
He added that the church is “working closely” with the Woburn Board of Health to help the agency with contact tracing. Mr. Davis said that within 24 hours of church officials learning of five of the cases, they contacted the health board.
Neither representatives from the health agency nor the mayor of Woburn responded to numerous calls and emails.
Susan Beachy contributed research.