Carlos Garcia leans back as a medical professional inserts a swab into his nose to collect a sample to test for the new coronavirus at a drive-through testing site at the Doris Ison Health Center in Miami in this March 20, 2020, file photo. Credit: Wilfredo Lee | AP

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For more than a month and a half, Maine has prioritized COVID-19 tests for the most at-risk patients: First priority goes to people who are hospitalized, health care workers, first responders and people living in congregate settings such as nursing homes. Second priority goes to people older than 60 and those with underlying medical conditions.

Maine, however, needs to be able to test everyone with symptoms, not just those at greatest risk of severe illness or death, in order to reopen its economy, Gov. Janet Mills has said.

Having enough testing capacity — for doctors to order COVID-19 tests for their patients whenever they need to, and get results quickly — would ultimately allow residents to better know if they could go to work or visit with friends, help employers make decisions about their business operations and allow public health agencies to better track and respond to emerging outbreaks.

[Our COVID-19 tracker contains the most recent information on Maine cases by county]

But what would it take to test everyone with symptoms? Researchers across the globe differ in their estimates of how many more people need to be tested and how frequently, leaving Maine public health officials to weigh a number of unknowns amid significant constraints.

And while there are bright spots in the world of COVID-19 testing in Maine, the stakes are high as the state begins rolling back restrictions on a limited basis.

Not having enough testing and screening for COVID-19 is one thing that keeps Rebecca Boulos, executive director of the Maine Public Health Association, up at night, in addition to not having a larger system of contact tracers who can identify people who come in proximity to positive patients.

Even with a small reopening, “I worry that we will see an increase in cases that we will be unable to track in a comprehensive way, and it will be difficult to ask people to back off again,” Boulos said.

Nirav Shah, who as director of the Maine Center for Disease Control and Prevention is overseeing Maine’s response to the pandemic, has estimated that Maine needs to double or triple its current testing capacity. The Harvard Global Health Institute estimates Maine needs to increase daily testing by about 50 percent to identify most infected people in a timely manner. The White House, meanwhile, has called for Maine to test more than three times what it’s currently testing each day.

A definitive answer on how much testing Maine actually needs to do is elusive.

“That is predicated on having a good sense of what percentage of people are symptomatic. We do try to track that through our various disease monitoring mechanisms, but I don’t have a number for you — to be totally honest with you — how many weekly tests we would need to perform,” Shah said in an interview. “It’s something I think about a lot.”

Gauging how much more testing capacity Maine needs is a moving target based not just on how much of the population is symptomatic or asymptomatic, but also how quickly or slowly the virus is spreading, and how fast a large number of laboratories that operate independently of one another can turn out test results.

But the unknowns don’t preclude Maine from trying to boost testing capacity, and any solution will likely hinge on Maine’s state laboratory in Augusta, the Maine Health and Environmental Testing Laboratory, which has been the engine for producing COVID-19 test results in Maine.

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An average of about 400 Maine residents are being tested each day, according to positive and negative case numbers reported to the state. Most people — about 300 each day, on average — are having their specimens processed by Maine’s state lab where staff are working overtime, seven days a week.

There are some encouraging signs. The lab does not have a backlog of tests, and it’s turning out test results quickly. If specimens come in before 10 a.m., the lab can send out results the same day, Shah said. If specimens come in later, the lab gets results out the next morning.

Maine also has a backstop. It can send tests to a commercial lab, LabCorp, if it gets overwhelmed. The Maine CDC made this arrangement at a time when the supply of chemical reagents to keep the state lab testing at full capacity was at its most uncertain, said Robert Long, a spokesperson for the agency. In early April, the state lab sent about 580 samples to LabCorp for testing, but it’s had enough capacity since then to test samples when they arrive.

There can be drawbacks to relying heavily on commercial lab testing. It can take longer to get results, Long said, and Maine incurs a per-sample cost.

While the capacity for testing in Maine will depend in part on what large laboratories such as Quest Diagnostics and LabCorp can accommodate, it’s also not clear how quickly they could turn out results if demand spiked nationwide. Long estimated that six to 10 labs have delivered COVID-19 results for Maine residents. They don’t need approval from the Maine CDC to test specimens.

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“We’ve tried to get some insight into what their capacity is. What they say is, ‘Send us what you’ve got.’ What they don’t tell you is they often run several day-long turnaround times,” Shah said. “We could probably send them every sample in the state, or we could send as many as doctors could swab, but their turnaround time might be five, six, seven days. When you’re dealing with a fast-moving outbreak, is that really capacity?”

Quest Diagnostics, which tests samples in 12 laboratories across the United States, says its test capacity outpaces demand. It is turning around test results in one to two days, on average. LabCorp also says it has no backlog.

Commercial labs don’t have to report their turnaround times to the U.S. Centers for Disease Control and Prevention, and they change day by day based on how many tests they have to run, Shah said. Any solution to expanding capacity in Maine will not rely on “just hoping and praying” that they can keep pace, he said.

The Maine CDC is “working quite feverishly on a solution that will greatly expand the testing capacity at the state laboratory,” he said, but “the deal is not yet done.”

In the meantime the state has been diversifying its machines that can detect COVID-19 using a polymerase chain reaction, or PCR, test. The state lab has a Roche nucleic acid extractor, and in February it purchased a QIAGEN machine. It has also ordered a $62,000 KingFisher instrument capable of processing 96 samples per run, which is expected to arrive this week and allow the state lab to turn out results for a total of 500 tests per day.

The idea is not only to expand but maintain capacity, Shah said. That’s because each proprietary platform requires chemical reagents that can only be purchased from specific vendors.

“If there’s a run on the supply of the Roche reagents, we’ve still got two other machines that we can use to help us do the extraction process,” Shah said.

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Getting those reagents has caused “the vast majority” of challenges with increasing testing capacity, he said. The reagents either come directly from manufacturers or the International Reagent Resource established by the U.S. CDC. The IRR has warned that “initially, supplier inventories will not satisfy demand” and has encouraged laboratories to only order reagent quantities that will last for one to one-and-a-half weeks of testing.

Getting a more precise handle on how the disease is behaving in Maine and therefore how much more testing is needed will rely, ironically, on increasing testing.

To get a better sense of the background rate of infection — the percentage of people who have the illness but don’t show up in reported case numbers — the Maine CDC intends to conduct randomized testing of Mainers who opt into a sentinel surveillance program, Shah said. But it needs more testing capacity first.

Sentinel testing would allow the state to actively test a large number of people, including those who don’t have symptoms, who don’t fit within the state’s current priority groups for tests. It is used when high-quality data are needed about a disease that can’t be obtained through regular, passive tracking methods.

New York conducted this randomized testing and discovered that more than 21 percent of about 1,300 people in New York City who were tested for coronavirus antibodies were found to have them, suggesting the true incidence of the virus was far greater than the recorded number of confirmed cases. However, though they are fast, it’s not clear how accurate the antibody tests are at detecting COVID-19. Shah said he would not rely on any antibody test currently on the market to conduct sentinel testing in Maine.

“We are working on developing plans for sentinel testing but using PCR, not antibody testing,” he said.

The U.S. Food and Drug Administration is fast-tracking approval of new COVID-19 diagnostic tests, and there are questions about how many false negatives may be occurring, but Shah said he is not concerned about the accuracy of the PCR tests that Maine is using.

“Generally, when there are inaccuracies with PCR, it has more to do with the manner in which the specimen was collected,” he said.

At least one outside lab is ready and willing to help boost the state’s testing capacity: Jackson Laboratory, headquartered in Bar Harbor. LuAnn Ballesteros, vice president for external and government affairs, said she sees a role for the research institution to test people who are asymptomatic — who likely make up a sizable percentage of those with COVID-19.

“I think where the Jackson Laboratory and other commercial testing companies could come into play is if the state decides to move to a strategy of testing asymptomatic people in order to confirm that the workplace is safe to return to and the workforce is safe to be together,” she said.

Jackson Laboratory has been working with Connecticut, where its COVID-19 testing lab is located, to expand testing capacity in that state. It’s processing about 550 specimens per day — acquired from nasal swabs but not saliva — with a guaranteed turnaround time of 24 hours. It is in the process of gearing up to 20,000 tests per day in the coming weeks.

The facility is “at the ready” to also help Maine, Ballesteros said. “We would welcome that opportunity, and we’ve offered it as well.”

While Maine is seeing some testing constraints lifted, it’s not to a point where it can test everyone. It will likely try to first expand testing among a particularly vulnerable population: people who live in congregate settings, such as nursing homes, Shah said.

“Our approach is to try to get a good handle on the general population, and provide testing for symptomatic folks, but really zero in on congregate care settings,” Shah said. “We are looking at how to model and think about universal testing in those settings. We’re not there yet but conceptually that’s where we want to go.”

Watch: Nirav Shah on risk

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Erin Rhoda

Erin Rhoda is the editor of Maine Focus, a team that conducts journalism investigations and projects at the Bangor Daily News. She also writes for the newspaper, often centering her work on issues of sexual...