Virus testing in towns across state a mixed bag. Eight of every 100 people have been tested.

Recently released town-by-town coronavirus testing data has provided new local context about Massachusetts’ battle against the pandemic.

In Rockport, for example, relatively few people have been tested but an above-average percentage has come back positive.

Testing has been just below the statewide average in Springfield and Holyoke, two of Massachusetts’ most diverse but economically challenged cities.

And in the Berkshire County hamlet of Sandisfield (population 972), nearly 12 of every 100 people have been tested for the virus, giving a town with few infections one of the highest per capita testing rates in the state.

The new data offered a glimpse of where testing has been most intensive, which includes cities that have been particularly hard hit by the pandemic, such as Chelsea and Brockton. The breakdown also showed testing has varied significantly from town to town, though the data made it hard to draw concrete conclusions.

Governor Charlie Baker’s administration published the information Wednesday after facing calls for more transparency. Public health experts and local officials have stressed the need for more granular testing data to fully assess the impact and infection rate among different communities.

More than 550,000 people have been tested in Massachusetts. As of Friday morning, the state had the sixth highest per capita testing in the nation behind Rhode Island, New York, North Dakota, New Mexico, and Louisiana, according to data complied by the Kaiser Family Foundation, a nonprofit that focuses on health issues.

Despite caveats with the latest data, the town-by-town breakdown did offer some new insights in a state where, on average, almost 8 of every 100 people have been tested.

Near the top of the list is Chelsea, where nearly 18 out of every 100 people have been tested. At the other extreme is Amherst, where the ratio is less than 3 people out of 100.

Boston — which mirrored the state testing average — has had twice as many people tested per capita compared with the adjoining town of Brookline.

The same was true in Gloucester, Chicopee, and Acton, which had testing rates roughly half that of Norwood, Leominster, and Worcester.

Communities of color have been hit harder

The new data underscored again how the virus has disproportionately impacted communities of color.

Cities and towns with large Latino populations have particularly high rates of positive tests. That includes Lawrence, Chelsea, Lynn, Revere, and Everett, where there has been more testing than in most cities and towns. But there are also high positive rates in other municipalities with large Latino communities — Holyoke and Springfield — where testing has not been as prevalent, according to the data.

The same high positive test rates can be found in cities and towns with large Black communities, including Brockton, Randolph, Boston, and Malden.

The opposite held true in the state’s larger towns with the highest concentration of white residents. Westport, Somerset, Hanover, Duxbury, and Hingham all have had substantially lower percentages of testing and positive tests.

Alarmed by the disproportionate impact on communities of color, public health experts and other advocates have urged the Baker administration to provide even more granular data. The administration has rejected a Globe request for coronavirus data by ZIP code and a breakdown of testing by race and ethnicity, both of which are provided in some other states.

The state Legislature recently passed a bill that is on Baker’s desk that would require the administration to provide more demographic detail in its daily COVID-19 updates.

One group pushing for more data is the NAACP, which is led in Boston by Tanisha M. Sullivan, who serves on the COVID-19 Health Equity Advisory Group for the Department of Public Health.

“We want to understand who’s gaining access to the test … versus who is told to go home and nurse symptoms,” said Sullivan, stressing the need for a breakdown by ZIP code, race, ethnicity, and gender. “Having that level of data will allow us to get a better snapshot of which communities, towns, and neighborhoods have access to the test, which is critically important from a racial equity standpoint.”

Pockets of infections

The data released last week also included the percentage of tests that come back positive for each city and town, which is often called the positivity rate. It made it clear there were pockets of infections across the state.

For example, there has been significant attention on the high prevalence of COVID-19 in Chelsea, but the new town-by-town positivity rates made clear there were similar concentrations in the nearby communities of Everett, Lynn, Revere, and, to a lesser degree, Malden.

To pinpoint broader trends, the Baker administration calculates a statewide positivity rate for the most recent seven days of testing. The new town-by-town rates covered all tests in the last six months, making it hard to analyze trends. There was no way to know, for example, if the high concentration of testing in Danvers was because of a blitz in testing last week or a steady progress over the past few months.

The data did suggest a recent surge of cases on the South Coast. In the last five weeks, the largest proportionate jump in positive cases have been in New Bedford, Fall River, and other nearby communities such as Somerset, Dartmouth, Fairhaven, and Westport.

Testing in institutions skewed numbers

In some ways, the town-by-town testing breakdown raised as many questions as it answered. At first glance, a number of smaller towns made the top 10 in per-capita testing: Shirley, Bedford, Gardner, and Ayer. But each town had a prison or other large institution that increased its testing numbers.

Shirley had the state’s highest testing rate — three-times higher than Boston, according to the state data. But Shirley is home to a sprawling state prison complex and nearly 70 percent of the town’s tests were on inmates.

Bedford had a high number in part because it is home to a veterans medical center and tests from nearby Hanscom Air Force Base are included in the town’s total, according to Heidi Porter, Bedford’s director of health and human services.

Gardner has a state prison. And Ayer? There’s a hospital, long-term care facilities, and one other large institution nearby.

“The federal prison at Devens," said Ayer’s health agent, Bridgette Braley. “I believe those [testing] numbers went into Ayer’s” totals.

Andrew Ryan can be reached at andrew.ryan@globe.com Follow him @globeandrewryan.