The coronavirus' more-transmissible delta variant has been detected in a cluster of cases being monitored in Provincetown through genetic testing, Massachusetts health officials announced Friday.
No other known variants were found in the review of the cases, done by the state's public health laboratory and by MIT's Broad Institute and Harvard, according to the Massachusetts Department of Health.
Officials also noted that, while people who have been fully vaccinated have been infected with COVID in Provincetown's cluster, there are still very few instances of vaccinated people getting the virus: just 5,166 cases out of more than 4.3 million people, or 0.1%.
Finding the delta variant in the Provincetown cluster, which has prompted a new mask advisory in the tourist town, is likely not a surprise -- the delta variant has become the dominant one in the U.S. Health officials noted Friday that the Centers for Disease Control and Prevention recently estimated that it made up 68% of New England's cases between July 4 and 17.
"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. These two factors contribute to the increased transmissibility seen with the Delta variant," officials said in a news release.
They urged people in Massachusetts to get the vaccinated, since that's been shown to effectively prevent serious complications from COVID and variants.
At least 256 coronavirus cases have been tied to the outbreak in Provincetown, many in people who were already vaccinated. COVID tests have been returning positive at a far higher rate there, at 12.3% between July 4 and 17, than on the rest of Cape Cod and in Massachusetts, which was 0.88% statewide over the same period, according to the state's COVID dashboard.