Covid-19 case counts declined slightly, but fully vaccinated residents continue to test positive on Martha’s Vineyard according to a weekly case update released by Island boards of health.

In the update, health agents reported 10 new symptomatic positive cases of Covid-19 between Sunday, July 18 and Saturday, July 24, a decline of six from the week prior.

But Tisbury health agent Maura Valley reported a combined five additional cases on Sunday, July 25 and Monday, July 26.

All 10 patients who tested positive last week were either fully vaccinated or under the age of 10, according to the report. Children 12 and younger are not eligible for the vaccine, according to CDC guidelines.

Four of the 10 positive cases are 10 or younger, and six are fully-vaccinated adults, Ms. Valley confirmed in a follow-up email with the Gazette. There have now been at least 12 breakthrough cases reported on Martha’s Vineyard, in which fully-vaccinated residents test positive for the virus.

“All of the positive adults last week were vaccinated and all had mild symptoms,” Ms. Valley wrote.

There are now 13 cases in progress on the Island, a decline from last week but an increase from late May and early June, when case counts dropped to near zero on the Vineyard. Ten of the cases are symptomatic.

The Martha’s Vineyard Hospital and TestMV — a free testing site located at the West Tisbury School — continue to offer Covid-19 testing during the week. Of the 10 cases last week, nine were tested at the hospital and one at TestMV.

Four positive Island test samples have also been sequenced for the Delta variant, a more contagious version of Covid-19, according to the report. There are currently two samples still pending at the state epidemiology lab.

“Not all cases are tested for variants,” the report said.

The Island continues to lead the state in Covid-19 vaccination rates, with 87 per cent of Dukes County fully vaccinated, based upon 2019 census data.

But the uptick in case counts mirrors state and national trends that have reported significant numbers of breakthrough cases across the country and region. In Provincetown, a case cluster grew to more than 500 people over the weekend, with about 70 per cent of the people who tested positive fully vaccinated, according to reporting in the Boston Globe.

The town has instituted an indoor mask mandate in response to the case surge.

Three hospitalizations associated with the cluster have been identified by health officials, according to the Globe.

The Island has not seen any case hospitalizations in recent weeks, hospital officials confirmed during a press briefing last Wednesday.

According to the CDC, all three available Covid-19 vaccines are known to significantly lower the risk of serious illness and hospitalization, although breakthrough cases are still possible.

The Island has now had 1,537 residents test positive for the virus, with 37 per cent linked to another case. There have been no Covid-related deaths on Martha’s Vineyard since the pandemic began in early March of 2020.