Covid-19 cases and case clusters continue to loom over the Island’s summer season, with August officially registering the most positive Covid-19 tests in a month since the pandemic began and the Martha’s Vineyard Hospital administering their first booster shots last Friday.

In a weekly case update, 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.

According to health officials, 41 cases are symptomatic, four are asymptomatic and 34 are unknown.

Although the 79 cases marks 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 19 cases after the update, including 11 on Sunday and eight on Monday.

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 — just as businesses seek to capitalize on 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 was closed Monday.

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 of last week and have since been in isolation, and segregated from other staff members.

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. However, staffing shortages and quarantine rules have forced closures across the Island throughout the month.

Since the start of August, 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. This 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 1,872 confirmed positive cases since the start of the pandemic.

Martha’s Vineyard Hospital has reported a spate of Covid-19 hospitalizations and four Covid-positive medical transfers during the month, including a critical airlift during the second week of August. There is currently no one hospitalized with Covid-19, according to hospital spokesman Marissa Lefebvre.

Hospital officials said that their sickest patients have been unvaccinated.

The hospital also administered its first handful of Covid-19 third vaccine doses last week. Officials said the hospital plans to call the first batch of eligible patients before a broader third-dose rollout later in the fall.

The hospital has given seven third-dose shots as of Friday, August 27. 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 wrote 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 3rd dose, and plan to provide an update in the coming weeks.”

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.

On Monday, TestMV completed its move from the West Tisbury School to the Agricultural Hall grounds. The free test site has administered more than 41,500 tests at three different locations since opening last May, identifying about 450 Covid-positive patients.

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