Wisconsin labs running far under COVID-19 testing capacity
As we’ve watched the coronavirus make its way around the world, noting its trajectories in different countries, a message has become clear: Widespread testing can limit the spread of the virus and is key to helping Wisconsin get back to something like normal.
In a month, the reported statewide testing capacity has shot up from two public labs running a few hundred tests to 30 active labs that could, in theory, process a combined 7,600 tests per day.
But far fewer tests are being processed than that capacity, which is based on a survey of labs administered by the state.
Thursday, for example, the state reported 1,800 new tests — less than a quarter of the labs’ self-reported abilities.
In fact, more tests were being conducted earlier this month, before many of the commercial labs came online. From April 1-10, an average of 1,750 tests were done each day; since then, the average has been 1,425.
Optimistically, it could be that tests are down because fewer people are infected by the coronavirus. But the decline comes even as state officials are stressing that patients can now be tested who were previously not prioritized.
“We are still not testing enough to facilitate the kind of contact tracing we’ll need to do moving forward, or to know the true prevalence of COVID-19 in Wisconsin,” state health secretary Andrea Palm told reporters Thursday, when Gov. Tony Evers extended the state’s safer at home order to May 26.
“We need a clearer picture, and the only way to take that picture is to further scale up our testing capacity,” Palm said.
So why is Wisconsin testing below its reported capacity? Does that number fail to account for shortages of key supplies? Do providers, who heard so much earlier about shortages, now believe there are no available tests, or that testing isn’t worth the cost in critical supplies? And is there less demand for tests?
What does ‘capacity’ really mean?
The capacity number reported by the state’s health department means that if all the labs currently testing received exactly that number of samples that day, they could test 100% of them, said Alana Sterkel, assistant director of the state lab’s communicable disease division.
But it assumes that all of those samples come in — an assumption that carries with it caveats of its own.
For example, Madison-based Exact Sciences recently expanded its capacity, a move which Sterkel said will ultimately add up to nearly 3,000 more tests being run per day.
But it will take time for the lab to connect with providers who will then submit patient specimens, she said. That extra capacity won’t get used right away.
And it’s also not clear that labs are understanding “capacity” the same way as the state lab, because Exact Sciences doesn’t actually say that it could do 3,000 tests today, if it got them.
An Exact Sciences spokesperson said the company is “planning on capacity for hundreds of tests near-term and thousands in the coming weeks.”
Labs also have good reason not to test at full capacity, Sterkel explained. Getting too close to that number would risk spilling over the top and causing a backlog of tests, which then sends the message to health care providers that they should reduce the number of patients they try to test. Some labs are still reporting these backlogs.
“If capacity exceeds the number we are actually testing, doctors can feel more confident that samples they send to the lab for testing will be tested quickly and without using up resources that are needed for critically ill patients,” Sterkel said.
In a Wednesday webinar update for labs across the state, Sterkel reiterated that labs themselves can’t control how many specimens get submitted for them to test, so it’s crucial to communicate with providers about how many tests the lab can handle.
Capacity may be increased, but labs face tough choices In the state’s early days of testing for coronavirus, the public labs urged providers to follow a tiered system in deciding who gets a test. Priority was given to hospitalized patients and health care workers who showed symptoms.
Now, with close to 30 labs testing as of Thursday morning, state officials are trying to get the message across that only the public labs are restricted by those tiers.
“There really should not be any restrictions,” Ryan Westergaard, the state’s chief medical officer of communicable diseases, told reporters last week. “Any provider, if they feel like it’s the best thing for their patient, can order a test and send it to one of these other labs.”
At UW Health in Madison, medical director of infection control and prevention Nasia Safdar said guidelines for who can be tested at their in-house lab are “pretty liberal.”
But even as their capacity grows, they’re testing below it, and not every patient who wants a test is going to benefit from that expanded capacity.
They’ve chosen to test each person who comes in for an essential procedure, and they’re not facing an imminent shortage of testing supplies — but if they were to begin testing everyone, Safdar said, their capacity could quickly get overwhelmed.
Bringing in a patient with mild symptoms, for example, means using personal protective equipment, a swab to grab the specimen, transport liquid to take it to the lab and reagents to run the test — all materials that are running low nationwide.
If the patient is likely to recover at home anyway, Safdar explained, the cost of using another round of PPE and testing materials may not be worth the outcome of a positive test result.
“If we had no PPE issues or capacity issues, we would send that (message of expanded capacity) out more strongly,” she said.
The same is true at Children’s Hospital of Wisconsin, which is also testing below capacity and ever-mindful of the possibility that the supply chain could reduce how many tests they can perform.
Right now, the hospital is testing any child who is admitted, as well as select symptomatic or exposed employees, said communications specialist Ashley Cobert.
Testing supply shortages still slow progress at some labs There’s a lot that goes into a coronavirus test. And many of those puzzle pieces are running low in Wisconsin labs.
An April 7 memo from Westergaard to the state’s health care providers notes the quandary of growing capacity with possible supply shortages ahead.
“While availability has expanded in recent weeks and is anticipated to continue to improve, both nationally and within Wisconsin shortages of supplies and access to testing is still a reality,” Westergaard wrote.
In early April, the State Emergency Operations Center surveyed labs across the state to see which supplies were short.
The most common results, Sterkel said, are reagent shortages, as well as trouble getting hold of cartridges for the molecular test GeneXpert, which she said has been “very slow” to make its way into Wisconsin because distribution was prioritized to states with more cases.
“We’ve seen fits and starts where the lab is ready and able and willing, but they’re just not getting the supplies to get going,” Sterkel said.
On the other end of the equation are clinicians, some of whom find it difficult to maintain a steady supply of test collection kits, including swabs used to collect the specimen and transport liquid to send it to the lab.
It’s been a challenge particularly for more rural providers, Sterkel said, who don’t hold as much purchasing power. So on Monday the SEOC launched a free distribution center to get the kits to providers who need them, a move Sterkel said was one of the state’s biggest testing-related accomplishments thus far.
These supplies, too, are limited: The state lab’s website cautions that providers should still use their own supply stream first and that the emergency kits are meant as a “temporary help” to allow a lab to keep testing.
Could demand for testing be tapering off ?
Beyond these explanations for why the state isn’t running as many tests as it could, there’s also another possibility — one that state officials, doctors and lab workers alike hope is playing a role.
There may just be fewer people now who want the test.
Wisconsin’s confirmed cases are growing slower than they did in early April, and according to the Wisconsin Hospital Association, fewer patients were hospitalized with COVID-19 on Thursday compared to a week prior.
“It’s certainly possible that there’s not a lot of tests needing to be done that are going undone,” said Westergaard, the state’s chief medical officer of communicable diseases. Westergaard noted that the total number of respiratory- related visits to outpatient clinics throughout the state are down, as are outpatient clinic visits in general. If respiratory illnesses are being controlled, fewer people might need testing.
The number of samples submitted for testing are decreasing across the nation, Sterkel added.
But testing is still important, she said, because it can help researchers understand which populations are most at risk from the virus, and guide states’ choices to enforce quarantines or other social distancing measures.