Since the pandemic began, Nantucket has tested 2,634 residents for Covid-19. Sandwich has tested 2,427 of its residents for the virus. Mashpee has tested 2,510. Bourne has tested 3,001. Falmouth has tested 5,955.

And Martha’s Vineyard has tested 6,579 residents for the virus, more than any town on the Cape, including Barnstable, despite having a much smaller population. In fact, four of the six Vineyard towns — Edgartown, Tisbury, Chilmark and Aquinnah — have among the highest testing rate in the state per 100,000 people, according to data from the state Department of Public Health. West Tisbury and Oak Bluffs closely follow.

The reason for the Vineyard’s high testing rate is a unique, public-private partnership that began six weeks ago to offer free, comprehensive coronavirus testing for asymptomatic patients on the Island. Spearheaded by seasonal residents Steve and Deborah Ruscowski, the Island boards of health and Island Health Care, the TestMV program started in late May and has since tested 4,435 people for the virus, hundreds of them seasonal or frontline workers.

“We feel great about that number,” said IHC executive director Cynthia Mitchell in an interview Thursday.

An advertisement that appears in the print edition of the Gazette this week also announces that TestMV has received a $150,000 donation to develop additional marketing and testing capabilities, including moving registration online. Seven families are listed as donors: Steve and Deborah Barnes, Dan and Mary Stanton, Mimi Haas, Allen and Shelley Holt, Gene and Carol Ludwig, Brian and Aileen Roberts and Len and Harriet Schleifer.

“We are expanding our community outreach to ensure everyone knows that no-cost testing is available. And we are working towards both an online registration process and on-site registration and testing,” the ad says, thanking the donors, who are all Island homeowners.

Ms. Mitchell confirmed the donation Thursday.

TestMV currently requires patients to call to schedule a test. The Martha’s Vineyard Hospital, which is testing symptomatic patients and their close contacts for the virus, had tested 2,202 patients, as of Thursday.

More than 60 people on the Island have tested positive for the virus — 16 of them through antibody tests, 47 through positive PCR tests and 11 asymptomatically at TestMV.

Although there have been some bumps in the road — including long wait times to schedule tests and lag times for patients to receive results — as well as gaps in coverage, especially for children, an analysis of data from the testing site and interviews with public health officials involved with the project show a nearly unmatched effort to offer widespread testing in a single location. And over the past six weeks, that effort has provided a unique picture of the virus’s spread on the Island, showing at least the partial extent of asymptomatic patients and likely halting its spread further, according to health officials working with the project.

“That’s been one of the main thrusts of this project,” public health nurse Lila Fischer said. “If we have widespread testing, we would have a better idea of the people with mild symptoms and stop the spread before it started. And that has happened.”

The project has a complex funding and operation structure that pairs the national testing company Quest Diagnostics (Mr. Rusckowski is the CEO) with Island Health Care, a federally qualified community health center. While Quest is responsible for providing and processing the tests, IHC is responsible for on-the-ground logistics at the high school site, administering the tests and scheduling them.

Quest has donated the testing supplies and a support team that helps IHC organizationally, according to officials involved with the project. The tests themselves are covered by insurance, according to Ms. Mitchell, with payments reimbursed to Quest. The site is staffed by a combination of paid IHC employees and volunteers. Ms. Mitchell said IHC received substantial funding from the CARES Act to administer the testing, and that the operation at the high school site has so far cost approximately $200,000, including marketing expenses.

MV Bank has donated $100,000 to help cover the cost of testing for individuals who do not have insurance. The testing facility opened May 28, initially prioritizing frontline health workers and employees at places like grocery stores and other essential businesses. Tisbury health agent Maura Valley said more than 300 of those individuals were tested in the first week ­— with all the tests coming back negative.

Two weeks and over 1,000 tests later, the test site received its first positive patient. By the end of June, the site had tested 2,298 individuals for the virus, with four tests coming back positive.

Over the course of the first month, the site tested 1,000 men and 1,298 women, with an age range spanning 79 years. The oldest patient to get tested was 98. No one under 18 can be tested at the site, although health officials said this week that they are working with school officials to make testing available for children.

Patients who get tested are required to provide a zip code for their main address. During the month of June, 1,931 individuals provided an on-Island zip code and 367 provided an off-Island zip code. The on-Island breakdown by town is as follows: 228 individuals from Aquinnah and Chilmark, 503 from Edgartown, 335 from Tisbury, 196 from West Tisbury and 657 from Oak Bluffs.

Since July 1, the site has gradually increased its testing capacity, pushing through nearly as many people over the past two weeks as it did in its first month. Ms. Mitchell said that the site is averaging approximately 180 to 190 tests per day, and is capable of testing as many as 250.

“There’s definitely been an uptick in demand,” Ms. Mitchell said.

The site has also had an additional seven people test positive for the virus, for a total of 11 positive cases. According to Ms. Valley, two of the cases provided off-Island addresses.

Looking back on the testing so far, officials said they were satisfied with the large numbers and on-site testing experience, but admitted that they were still working through complications on both the back and front end of the process, including scheduling and result times for the tests.

“People sometimes see the test center, and see that it’s not really busy, and don’t understand why we can’t just push more people through it,” Ms. Valley said. “But it’s on the front end and the back end, being able to schedule the appointments and do the follow up, that limits capacity. With that being said, we got the numbers up over 200 a day.”

“We’ve gotten no negative feedback on the experience of getting the test,” Ms. Mitchell said. “I give very high marks to the volunteers.”

But wait times at the call center, especially on Mondays, can be in the two-hour range to schedule tests, and some patients relying on a phone call for their test results have not received one in the 48-hour time period. Responding to questions about long wait times and the lag in response, organizers have instituted new protocols at the call center, like allowing patients to hang up and get a call back, and suggesting patients use the MyQuest app for results. Even so, the booking rate — the number of people scheduling tests divided by the number of people calling — was 77 per cent between July 6 and July 11, which Ms. Mitchell called “good.”

She said the donation announced this week will go toward improving online and onsite registration, as well as improving wait times and increasing capacity.

“The customer service aspect of it, from registration and scheduling, the wait times have been problematic for people,” Ms. Mitchell said. “We would love to improve that. That is part of expanding capacity, to improve the customer’s experience to register and schedule the test.”

Organizers said six weeks ago they did not know what testing asymptomatic patients would reveal — partly because the Vineyard would be one of the few places in the country where it was widely available to all residents. The results have been illuminating and surprising.

“We really had no idea what to expect,” Ms. Valley said. “We learned that there are people on the Island who are asymptomatic who do have it. We learned that the business community is really receptive to this resource, so that they can try to protect themselves and their employees. And we learned that a lot of the seasonal workers that come to the Island are very receptive.”

The site is on track to reach its 10,000 test goal by the end of August, and Ms. Mitchell said she hoped to see testing continue beyond Labor Day, even if it means changing locations. More interesting than the number of tests, however, is the rate of positive tests: 0.02 per cent — one of the lowest numbers in the state.

“I don’t think we expected that. But I think it’s statistically . . . infinitesimal,” Ms. Mitchell said. “Does that mean it will hold? Nobody knows. But that’s why all the other things we’ve been involved with, masking, contact tracing, is all just so key.”