A look at how COVID-19 cases are increasing on Cape Cod

Melanie Phinney, left, prepared Canice McGarry of Brewster for her vaccination at Cape Cod Community College in Barnstable.Lane Turner/Globe Staff

Cases of COVID-19 are rising on Cape Cod, causing alarm from local health officials and illustrating the continued threat posed by the virus and its variants even as vaccinations ramp up across the state.

Both COVID-19 case numbers and positivity rates have increased in recent weeks on the Cape, with about half of the region’s communities now considered to be at high risk for the spread of the virus, according to the state’s latest town-by-town report. In some towns, the increase is threatening to erase progress made in the wake of the winter surge, even as the Cape leads the state in the share of its population that has been vaccinated.

In response to the rising numbers, Yarmouth Health Director Bruce Murphy warned the region could be witnessing a “third wave” outbreak and called on state officials to redistribute some doses from mass vaccination sites to community clinics on the Cape and set up an emergency vaccination site in the region.

“We need to get ahead of this now,” Murphy told the Globe.

According to state data released Thursday, the town of Barnstable has by far the highest average daily incidence rate in the state, at 64.6 cases per 100,000 residents. Barnstable, the largest town on the Cape, also had the highest positivity rate in the state, with 10.2 percent, for cases from March 7 to March 20.

Additionally, nearby Yarmouth had a high average daily incidence rate per 100,000 residents with 39.2 and a high positivity rate with 7.98 percent.

“We need emergency vaccination sites down here for that section of the population that we might be seeing an increase in,” Murphy said about the rising cases.

“I know they’re looking at doing emergency vaccination sites around Boston, but it would seem that you would need one down here if that’s where I believe the epicenter is of the third wave. I know they mention the uptick is coming, I’m saying this is the epicenter of the third wave on the Cape between towns increasing in the high risk and the P.1 variants really increasing down here,” he added.

While key metrics in Yarmouth, Barnstable, and other Cape communities trend upward, indicators of COVID-19′s spread in Massachusetts have remained lower. As of Thursday’s weekly report, the state’s average daily rate of infection per 100,000 residents was at 21.5, and Massachusetts’ positivity rate was at 2.01 percent, according to the most recent state data.

The figures in Barnstable represent an increase from data released the previous week, in which the town had an average daily incidence rate per 100,000 residents of 45.1 and a positivity rate of 7.49 percent.

The number of towns on the Cape that have slipped into a “high-risk” designation has also increased over the past few weeks. In the state’s report released on March 11, there were no Cape communities considered to be high risk for COVID-19. But by Thursday, according to the state data, seven of 15 Cape communities were designated high risk.

Sandwich, Mashpee, Barnstable, Yarmouth, Dennis, Harwich, and Brewster all met the state’s minimum thresholds to be considered high risk for the virus. In the previous report, only Barnstable and Yarmouth were designated as high-risk communities.

The increase in positive cases and positivity rates in Cape communities does not appear to be solely a result of increased testing, according to a Globe review.

Eleven of the towns on Cape Cod had an increase in positivity rate since March 4, but only five had an increase in testing over that same timeframe.

The increase in cases on the Cape comes even as the region, which has a population that skews older, leads the state in COVID-19 vaccinations as the state prioritizes its most vulnerable residents in its vaccination rollout plan.

According to state data released Thursday, 39 percent of residents in Barnstable County, which encompasses all towns on Cape Cod, have received at least one COVID-19 dose as of March 23, the highest rate in the state. Overall, 29 percent of Massachusetts residents have received at least one dose of the COVID-19 vaccine.

Yarmouth Health Director Murphy said he thinks the increase in cases in the town and on the Cape is a combination of factors, including the arrival of the P.1 variant in Barnstable County.

In late February, the COVID-19 variant that originated in Brazil was identified in a Barnstable County woman in her 30s, state officials said.

“It’s concerning when I look at the statistics for Yarmouth and then I look at what else is happening on the Cape over the last two weeks,” Murphy said.

The state has informed Yarmouth that the P.1 and UK strains are becoming more common on the Cape.

“Between Sandwich, Barnstable, Yarmouth, and Dennis, we’re seeing more of the P.1 cases,” he said. “And [the UK variant] is increasing so much the DPH isn’t notifying the towns because it’s getting so common out here.”

The state’s COVID-19 command center said in a statement that it is working with Barnstable County to address the spike in cases and is providing mobile testing sites in the region this week.

“The administration has worked with Barnstable County to help open 13 COVID-19 vaccination sites and Barnstable County residents are leading the state for vaccines doses, with 41% of residents having received a first dose and 24% of fully vaccinated - the highest percentages of any county in the state,” Kate Reilly, a command center spokeswoman, wrote in an e-mail.

This graph shows the number of active daily COVID-19 cases in Yarmouth.Town of Yarmouth

The Brazilian variant is less studied than other “variants of concern” found in the United States, William Hanage, an associate professor of epidemiology at the Harvard T.H. Chan School of Public Health, told the Globe last week. But specialists believe it could be more transmissible than COVID-19, capable of reinfecting people who have recovered from the virus, or “some combination” of both, he said.

Martin Finucane and Travis Andersen of the Globe staff, and Globe correspondent Lucas Phillips contributed to this report.