More than two months after the first confirmed coronavirus case here, Maine is the only state in the country that does not compile daily reports on the number of people who have been tested for it.

The shortcoming means public health officials and others are hampered in monitoring a key metric in tracking the spread of the disease to detect new flare-ups and guide reopening plans: the proportion of people who are testing positive for the virus.

The Maine Center for Disease Control and Prevention compiles the total number of negative tests on state residents only once a week, meaning the agency can also determine a critical metric – the so-called “positivity rate” – only weekly. As the Portland Press Herald reported April 14, every other New England state has compiled and released negative test counts since March, even though at least three of them relied on outside laboratories for part of their testing.

A week ago, The New York Times published a data article showing that few states that were reopening met the White House’s guidelines for doing so, particularly the daily trends in the positivity rate and the trend in the number of cases administered. Maine was the only state excluded from these and other charts, the newspaper reported, “because consistent and reliable data on testing in the state was not available.”

The positivity rate is not an obscure piece of data. At his news briefing Monday, Maine CDC Director Dr. Nirav Shah repeatedly highlighted its importance when questioned about how the state was evaluating the safety of the phased reopening, which included the May 11 reopening of most retail activity in 12 of Maine’s 16 counties.

“This metric I go back to a lot, which is the positivity rate, seems to be holding steady if not trending in the right direction,” Shah said. “If the positivity rate stays the same even if we triple the amount of testing (or) if it goes way up even as we triple (the) tests … that tells us a different epidemiological story.”

In epidemiology, positivity rate is often used to track the spread of deadly diseases in circumstances where most people can’t get tested and gives an indication of whether a testing regime is casting a wide enough net. If the positivity rate fails to shrink as testing expands, it’s a bad sign, as it indicates a lot of cases are going undetected in the community.

Dr. Patrick Remington, professor emeritus of the University of Wisconsin-Madison School of Medicine and Public Health, said Maine’s once-a-week approach is unwise because it deprives the state of complete information. “The more information we have, the better decision making can be,” Remington said. “It just doesn’t make very good math sense not to take advantage of the fact that every day you have a new piece of information.”

“If it seems to work in most places, then it becomes a standard of best practice,” he added.

Dr. Jennifer Nuzzo, an epidemiologist at the Johns Hopkins Bloomberg School of Public Health, said it is a bad idea to look at the positive test ratios only once a week. “You don’t want a week to go by before realizing you have a problem,” she said, “because that’s a week you lost in terms of being able to implement changes.”

Jeremy Youde, who studies the intersection of government and public health at the University of Minnesota Duluth, said having a daily measure of the positive COVID-19 results is essential for public health authorities. “In a state where you have reopenings varying by county, a once-a-week count is just not going to be a sensitive enough instrument to know if these (reopening) decisions are the right ones,” he said.

“The fact that Maine is the only state in the country where this information isn’t coming suggests that at some point in the chain something is not happening and there should be some opportunity to learn from other states what they are doing and be able to adapt the infrastructure of the Maine CDC to do that,” he added.

The Maine CDC’s explanation has shifted. A month ago, agency spokesman Robert Long said the problem lay with the differing formats used by the outside laboratories that have made up the majority of Maine’s testing, though it was not clear why at least three New England states that also use outside labs were able to overcome these challenges. He said the agency was working with outside labs “to develop a more consistent system for reporting negative test results.”

But this week Long told the Press Herald via email that the Maine CDC is sticking with weekly compilations as a matter of policy.

“Other states with significantly more cases might find greater value in measuring testing trends from day to day, but week-to-week trend analysis has met our needs to date,” Long wrote. “Maine CDC remains focused on making the best use of available resources to meet the needs of Maine people.”

Asked whether the agency is concerned that it is the only state not compiling testing data daily, Long suggested Maine’s rural character and relatively low COVID-19 prevalence make it unique.

“Conditions in Massachusetts or New York differ from those in Maine, so the responses differ,” he wrote. “Much higher case counts and far more densely populated urban centers in those states guide testing strategies that reflect different challenges than what Maine faces.”

He did not offer an explanation as to why at least five states with lower per-capita disease prevalence – Oregon, West Virginia, Alaska, Hawaii and Montana – are tracking the positivity rate on a daily basis, as is New Brunswick, which has only two active cases province-wide and hasn’t seen a new case in a week.

The Press Herald has had a standing request since May 5 to interview Shah about this and other testing issues connected with the reopening plan, but has been repeatedly told he is not available.

White House guidelines have said that any state seeking to end its lockdown should first have a downward trajectory of cases over a 14-day period before reopening. Maine’s active cases were growing in the two weeks prior to the commencement of phase one reopening on May 1, but the guidelines say a state could still reopen if its test positivity rate had declined over the two-week period.

As of May 6, Maine had reported 22,092 cumulative negative tests and 1,254 positive ones, for a positive test rate of 5.3 percent. Two weeks earlier, Maine had 16,784 negative tests and 907 positive ones, for a rate of 5.1 percent, indicating the state was not meeting the criteria.

The Maine CDC has also lagged in gathering or disclosing other types of data relating to the pandemic. It is the only state in New England that reports COVID-19 cases by county instead of by town. The agency was unable to say how many COVID-19 patients were hospitalized on a given day – a key metric of the burden on hospitals – until April 10, three days after the Press Herald published a story on the shortcoming. The agency had not even asked hospitals for the information until March 31. It was also unable to provide an accurate count of intensive care unit beds and ventilators until the week of April 5, more than three weeks after the first confirmed case in the state.

Massachusetts provides detailed information on the number of people hospitalized with COVID-19 at every hospital in the state, as well as the number of confirmed cases at each of the state’s long-term care facilities. The Press Herald has gathered and published the data from the hospitals for each of the past four weeks, but CDC spokesman Long has said the state would not release information on long-term care facilities that have had fewer than three confirmed cases.