Health officials say they suspect the more virulent Delta variant of the coronavirus is responsible for an expanding cluster of Covid-19 cases in Provincetown, Massachusetts.
The Massachusetts Department of Public Health said in a statement Friday that genetic sequencing of initial samples associated with the the Provincetown cluster tested positive for the variant.
It said two labs, the Massachusetts State Public Health Laboratory and the Broad Institute of MIT and Harvard, have "identified the Delta variant in cases associated with this cluster."
No other variants have so far been connected with the cluster.
"The Delta variant is known to be more transmissible than the original COVID-19 virus," the department said. "Individuals infected with the Delta variant tend to have more virus in their respiratory tract than other variants and infected individuals may carry the virus longer."
About 83 percent of new Covid-19 cases in the U.S. this month are Delta variant infections, and experts say the variant is behind the new wave of nationwide infections.
The Provincetown Board of Health said in a statement that Covid-19 cases increased following the 4th of July holiday weekend.
Health officials are "urging Provincetown’s residents, local businesses, and visitors to take precautions to reduce the spread of COVID-19, regardless of vaccination status," it said.
The board noted that masks are required for unvaccinated people 12 or older and advised indoor use when social distancing is not possible. Vaccination is the best way to avoid serious illness related to the coronavirus, it said.
The state Department of Public Health said Friday that 0.1 percent of 4.3 million fully vaccinated people in the state have tested positive for Covid-19. Health officials urged anyone with symptoms to get tested.