With an August spike in the rearview mirror, cases of Covid-19 on Martha’s Vineyard declined for the third week in a row and vaccination rates continued to inch higher, according to weekly virus reports.

In a truncated weekly update, health agents reported 40 cases of Covid-19 on the Island between Monday, Sept. 6 and Sunday, Sept. 12 — a 22-case decline from the week prior.

After peaking at 97 weekly cases during late August, cases declined to 79 new positive tests before the lower numbers these past two weeks.

“It’s continuing the downward trajectory,” Chilmark health agent Marina Lent said. “It’s exactly the same downward slope we’ve seen the past two weeks.”

According to the report, 65 per cent, or 26 of the 40 new positive cases, were among vaccinated people, while 25 per cent of the cases were among unvaccinated people. An additional 10 per cent of cases were unknown.

Ms. Lent said the high percentage of cases among vaccinated people piqued her interest, but explained the phenomenon by noting that the Island has a significantly higher proportion of vaccinated than unvaccinated residents.

“It’s just that more people are vaccinated,” Ms. Lent said. “We wouldn’t want to see what our rates were like if we were 20 per cent vaccinated on the Island.”

There is currently one person hospitalized with the virus at Martha’s Vineyard Hospital, according to the hospital’s most recent update, as of Sept. 10.

According to the report, 23 per cent of the cases, or nine out of the 40, were among people in their sixties, and three were above the age of 70 — countering recent trends that saw the majority of new cases among people in their twenties and thirties.

And with schools back in session, only three cases were reported among people under the age of 20.

Seven of the 40 new positive cases were confirmed by over-the-counter tests. Ms. Lent encouraged people who test positive through over-the-counter exams to call their health agents to confirm the positive test and go through proper contact tracing protocols.

The Island has also seen an increase in its percentage of vaccinated residents, according to state metrics, with 97 per cent of people over 12 having received two shots and 110 per cent receiving at least one dose. The percentages are likely high because they are based on 2019 Donahue institute population estimates for Dukes County, but have continued to inch higher after flatlining in the low nineties earlier in the summer.

The hospital has administered 14,340 complete vaccinations, and 110 third-dose vaccinations for immunocompromised or high-risk residents. A broader third-dose rollout is expected later this fall.

“The vaccine is remarkably good at preventing severe disease. It really has been,” Ms. Lent said.