Island health officials reported 27 new positive cases of Covid-19 last week, bringing case counts down to pre-summer levels after an August spike.

In a weekly case update, health officials said that 18 of the cases were symptomatic, four were asymptomatic and five were unknown.

The new weekly cases also continued a trend that has seen more cases among vaccinated than unvaccinated people, with 11 cases coming among vaccinated residents, one among partially vaccinated people, nine among unvaccinated people and six unknown.

Overall, 206, or 48 per cent of the 427 cases reported since July, have come among vaccinated residents. About 33 per cent, or 140 of the 427 cases, have come among unvaccinated residents.

Health officials have noted that the Island maintains a high rate of vaccination, meaning there are far more vaccinated than unvaccinated residents, in explaining the relatively high rate of breakthrough cases. According to state public health data, 97 per cent of Dukes County's 2019 Donahue Institute population estimate is fully vaccinated.

Cases have fluctuated throughout 2021. — Island Health Agents

The weekly report encompasses Sunday, Sept. 12 through Saturday, Sept. 18, and represents the fourth straight week that case counts have declined on the Island after peaking at 97 in mid-August. Weekly cases dropped to 79, 62 and 31 in prior weeks.

Although health officials reported 40 cases in the Sept. 5 through Sept. 11 report, nine of those cases included numbers from Sunday, Sept. 12, Tisbury health agent Maura Valley explained when reconciling the numbers.

“They are declining,” Ms. Valley confirmed.

In total, the Island has reported 1,992 confirmed positive Covid-19 tests, with approximately 100 additional probable cases or over-the-counter cases since the pandemic began last March.

While only nine per cent of cumulative cases have come in the zero to 10 age group, 19 per cent of the past week’s cases came among children under the age of 10. Children under 12 are not currently eligible for any of the available Covid-19 vaccines.

Health officials did not report any new clusters of Covid-19 cases in the weekly report, or related business closures.

Martha's Vineyard Hospital spokesman Marissa Lefebvre confirmed that there have been no Covid-positive hospitalizations or transfers since Sept. 7. The hospital has performed 47 first dose vaccinations, 75 second dose vaccinations and 20 third dose vaccinations during that period. 

"We're currently administering third vaccine shots to immunocompromised individuals who have specific medical conditions or who are receiving medications or treatments that weaken their immune response," Ms. Lefebvre wrote. "We're awaiting formal guidance from the CDC and Mass General Brigham on how best to operationalize booster shots. We expect to learn more in the next week."

Cases continue to climb statewide, with state Department of Public Health officials reporting an average of more than 2,000 daily cases.