As Labor Day weekend arrives, a second summer of Covid-19 continues to loom over the Island with case counts staying high, including many clusters among businesses fueled by the relentless Delta variant.

August officially registered the most positive Covid-19 tests in a month since the pandemic began.

And while the Island remains open, some large events are being cancelled, and vaccine mandates for government workers are under active discussion.

Following the lead set by Tisbury last week, Edgartown decided to postpone its 350th anniversary celebration to a later date.

Marking a first on the Island, on Wednesday the West Tisbury select board voted to adopt a universal vaccination policy for all employees, volunteers and interns who work in town buildings. The requirement takes effect Sept. 30.

And last Friday the Martha’s Vineyard Hospital began administering its first booster shots.

In a weekly case update Monday, Island health agents reported 79 positive PCR tests and six probable positive cases between Sunday, August 22 and Saturday, August 28, with 35 coming among fully vaccinated people, one among partially vaccinated people, 22 among unvaccinated people and 21 unknown.

Although the 79 cases mark a decline from the prior two weeks, in which the Island saw 87 and 97 cases respectively, Tisbury health agent Maura Valley confirmed that there have been at least 330 cases in August of 2021, surpassing the previous monthly high of 316 in April of this year.

Health agents reported an additional 49 cases from Sunday through Thursday this week.

Cases have risen sharply since the beginning of August, with the Delta variant present on the Island and at least 10 businesses forced to contend with clusters of Covid-positive staff in the peak summer month.

Nearly a dozen restaurants and retailers have closed due to staffing challenges imposed by Covid-19, including recently Rosewater Market and Takeaway, which closed Monday and remained closed at press time Thursday.

Health agents reported four new case clusters in Monday’s report. Three staff members each at the Sand Bar Grille restaurant and Nancy’s restaurant in Oak Bluffs tested positive for the virus, as well as six staff members at the Sydney Hotel in Edgartown.

Five staff members at the Vineyard Haven Cronig’s Market have also tested positive for the virus.

Speaking to the Gazette by phone, Cronig’s owner Steve Bernier said the staff tested positive for the virus on Monday the previous week, and have since been in isolation.

The store remains open, Mr. Bernier said.

“Employees at all three stores have been tested. We have segregated the five people who were involved,” Mr. Bernier said. “We’re limping along and we’re holding things together. And this week we’re hoping things get better as volume winds down a little bit.”

Businesses are not required to close if staff test positive for Covid-19. But staffing shortages and quarantine rules have nevertheless forced closures across the Island throughout the month.

From the start of August through last Saturday, 47 per cent of cases, or 146 out of 311, have been among fully vaccinated people. Another 31 per cent, or 96, have come among unvaccinated people.

And following recent trends, a disproportionate number of new positive Covid cases are coming among young people. Last week, 28 of the 79 cases, or 35 per cent, were among people in their twenties — about double the overall rate of 19 per cent.

Overall, the Island has reported 1,921 confirmed positive cases since the start of the pandemic.

The Martha’s Vineyard Hospital has reported a spate of Covid-19 hospitalizations and four Covid-positive medical transfers this month, including a critical airlift during the second week of August. There was no one hospitalized with Covid-19 at press time Thursday, according to hospital website.

Hospital officials said their sickest patients have been unvaccinated.

The hospital also has begun its third-dose Covid vaccine program. Officials said they plan to call the first batch of eligible patients before a broader third-dose rollout begins later in the fall.

The hospital administered 50 third-dose shots on Wednesday, for a total of 60 so far.

The shots are recommended for patients eight months after their second Covid-19 Moderna or Pfizer vaccination.

“Currently, only individuals with specific immunocompromising conditions are receiving a third dose,” spokesman Marissa Lefebvre said in an email. “These individuals were contacted directly by MVH to schedule their appointment. We are still working out a process for when more people become eligible for the third dose, and plan to provide an update in the coming weeks.”

A total of 17,404 people have been vaccinated in Dukes County, according to the state.

Covid-19 testing remains available for symptomatic patients and their close contacts at Martha’s Vineyard Hospital, while free, asymptomatic testing is continuing at TestMV from 9 a.m. to 1 p.m., Monday, Tuesday, Thursday and Friday, now located at the Agricultural Hall grounds in West Tisbury.

Tests can be scheduled by going to the TestMV website or calling 877-336-9855.