As Pennsylvania looks to restart at least some of its economic activity, everyone agrees more testing for the coronavirus is necessary. But almost no one seems to know yet how exactly it is going to happen, or what the expansion will look like.
Gov. Tom Wolf’s plan to reopen the state, unveiled Wednesday evening, asserts that “diagnostic testing capacity will be a critical factor” in tracking new outbreaks of the virus. Testing “will consist of a multilayered approach” that involves hospitals, doctors, health officials and other providers like pharmacies.
But asked Thursday morning how many tests the state wanted to see being performed before it would lift restrictions, Wolf said, “I don’t have specifics on the tests. And every day we keep talking about, ‘what does that actually mean?’”
A spokeswoman for Allegheny County confirmed that as of Thursday afternoon, the county had not been given any direction about what kind of testing the state expected to see. Nor was it clear when that information would be forthcoming, although the state says it hopes to begin easing restrictions in some areas by May 8.
“We’re waiting for guidance,” she said.
A number of factors complicate efforts to come up with a testing policy.
For starters, there has been a nationwide shortage in testing capacity since the onset of the disease. Shortages of reagents and swabs used to conduct most tests have plagued states all across the country. Wolf himself suggested the state might have to take matters into its own hands by tapping laboratories to start producing tests — though again, he offered few specifics.
It’s also not clear how much testing is necessary or realistic — especially in a place like Pennsylvania, where the disease has such varied impacts from one community to the next. Ten of its 67 counties have a case load in the single digits, while 12 counties have caseloads in the four- or five-digit range.
One Harvard University study recommended that by late July, testing should be carried out on up to 6 percent of the population each day. In Pennsylvania, that would amount to more than 768,000 people each day – more than the combined population of Butler, Washington and Westmoreland counties.
A less ambitious testing program — which is based on trying to ensure that positive test results make up no more than 10 percent of total results reported — envisions testing just 0.15 percent of the population per day. That would amount to testing 19,500 state residents per day, and 1,850 in Allegheny County.
Even that far more modest program, however, far outstrips current testing levels. On Wednesday, Allegheny County Health Director Dr. Debra Bogen said the county was currently carrying out between 300 and 400 tests per day — and that was a decrease from a peak of 500 to 600 in early April.
“We don’t know why the number of people being tested is dropping,” she said, noting that new test sites have opened in recent days.
Bogen said the overall county case count was “very encouraging,” with a long-term decline in positive cases. Still, she said, “only about 1 percent of our county has been tested for COVID-19, and it’s difficult to make decisions about 1.2 million people in the county when you have data on only 1 percent.”
“Testing has been fairly limited until now, and I think it’s just beginning to open up,” Bogen added. “And I hope in the next week or two we’ll really see much more wide availability of testing so we can really understand how much COVID-19 is out here.“
One central question is the extent to which authorities should seek to test people who are asymptomatic. People carrying the disease can transmit it to others while showing no or only mild symptoms themselves.
Bogen said the county doesn’t yet have the ability to test the asymptomatic, in part because it is not clear when a test would be most effective for someone carrying the virus without symptoms.
“This is something that is controversial in the field: how much asymptomatic testing do you need to do, and what criteria govern the context where they may spread?” said Dr. Amesh Adalja, a senior scholar at the Johns Hopkins Center for Health Security and a Pittsburgh-based infectious disease and critical care physician.
Adalja says it is difficult to create a one-size-fits-all standard for testing when communities vary so widely.
“There are very rural areas with very low population densities and very low penetration of this virus, and they don’t need the same type of testing as, for example, Philadelphia might. If I were given a thousand test kits, I wouldn’t give them to every county. I’d give them to Philadelphia.”
But he added that even some rural counties might need more attention. One red flag, he said, is a community where a large number of tests are coming back positive. That may sound like a mark of testing efficiency, but researchers say it can also be a warning sign: If one-quarter or one-third of those tested come back positive, it’s a safe bet that there are many positive cases going undetected. Most researchers say roughly 10 percent or fewer tests should come back negative.
In Allegheny County, about 8 percent of test results are coming back positive. But there may be trouble in both counties large and small. More than 40 percent of tests in Columbia and Juniata counties have been positive for COVID-19. In all, more than two dozen counties have reported positive test rates of 15 percent or more, according to state data, and not all of them are in the state’s most populous southeast region.
Adalja says any testing formula the state comes up with will have to be flexible. As for calls to test 6 percent of the population each day?
“I don’t think testing that big a percentage is feasible or necessary. There isn’t a magic formula. It has to do with how bad your region has been hit, what your population is, what is your hospital and testing capacity is. It will definitely be different for different counties.”
But in any case, he said, “We need testing to be a keystone part of how we move forward. A doctor should be able to order a test for anyone they believe may benefit from it, and not be worried about whether or not they are pinching the supply.”