COVID-19’s missing cases

Every day, Wisconsin counties and the state Department of Health Services (DHS) post new updates on the number of people infected and the number who have died from COVID-19.

The numbers creep up unevenly from day to day. On Monday, April 27, DHS logged 170 new cases, for a statewide total of 6,081 people who have tested positive for the SARS-CoV-2 novel coronavirus. The total number of confirmed deaths from the disease to date: 281.

But with all those numbers, there’s an important qualification. An unknown number of people in the state have COVID-19, and neither they, nor their family members, doctors or other healthcare providers know it. Some people have died from COVID-19 although they were never diagnosed before their death. And while some COVID-19 fatalities have been detected in tests conducted after they died, others have probably never been detected.

“We’re not measuring the true number of cases,” Dr. Ryan Westergaard, chief medical officer for the DHS Bureau of Infectious Diseases, said during a department media briefing on Monday. “We’re measuring the subset of people that are tested.”

It’s simply impossible for state officials to know how many people might have the infection — or might have died from it.

That’s one reason that, effective Friday, April 24, DHS Secretary-designee Andrea Palm and Gov. Tony Evers extended the state’s Safer at Home order. The order, first implemented March 25, now expires May 26, although Republican legislative leaders are suing in the Wisconsin Supreme Court to overturn the action.

The extension — and the state’s reopening plan laid out a week ago — will allow for a key step: testing more people and then tracing their interaction with other people who may have either caught the virus from them or transmitted it to them.

“Rapidly and dramatically increasing our testing capacity, and recruiting enough contact tracers to follow up on positive tests, will give us the tools we need to contain this virus,” Palm said Monday. “Testing will show us the spread of the virus, and tracing will enable us to help individuals who test positive for COVID-19 to quarantine and to stop continued spread.”

The state has now reached the capacity for conducting nearly 11,000 tests a day, within striking distance of a goal for 12,000 daily or 85,000 a week. DHS also has a goal of hiring 1,000 contact tracers.

Estimates and projections

When testing in Wisconsin began, DHS officials told doctors around the state to give top priority for tests to patients who were hospitalized with symptoms of COVID-19 and healthcare workers who also had symptoms. That was necessary because of concerns about shortages of testing materials as well as labs available to conduct tests, and at the time DHS acknowledged that there were probably many people with the illness who would not be tested.

“If you limit the testing only to severe cases, then you will obviously have a biased sample,” says Dr. Patrick Remington, who directs the preventive medicine residency program at the University of Wisconsin-Madison School of Medicine and Public Health. “You will miss mild cases and you’ll miss asymptomatic cases.”

Because of that, “I think it’s reasonable to assume that we have not diagnosed all asymptomatic cases — we certainly have not,” Remington says.  “We know that there’s community transmission [of COVID-19], so there are people who are out and about who probably don’t know they are infected.”

Projecting how many requires an educated guess and a lot of “ifs.” Remington tells the Wisconsin Examiner that the state test data appears likely to be capturing most COVID-19 patients who are seriously ill and hospitalized. But early indications are that as many as half of the total number of people carrying the virus don’t have symptoms. Additionally, many infected people with mild symptoms have probably not been tested either.

So, considering the number of people tested, “I don’t think it unreasonable to say [the actual total is] anywhere from two to three times that number — perhaps even more,” Remington says.

For Wisconsin to lower the Safer at Home order and “go safely back to business,” says Dr. Malia Jones, a health geography scientist at the UW Applied Population Laboratory, testing needs to be ramped up considerably, with contact tracing to accompany it.

“If you’ve got a runny nose, you should get tested,” Jones says. “If you’ve got a reasonable suspicion you could have it, you should get tested. Anyone with a reasonable suspicion of illness or exposure should be able to get a test. That’s not all 5.7 million people in the state of Wisconsin, but it’s a lot more than can get the test right now.”

DHS is now telling healthcare providers that they should feel free to order tests for anyone with symptoms, as Westergaard has said in several recent department media briefings.

Healthcare providers haven’t all caught up with that aspiration, however. At the Marshfield Clinic, for example, John Gardner, director of communications, says in-house testing “is focused on patients who need to be hospitalized, healthcare workers and/or those whose symptoms merit a COVID-test,” using an “internal algorithm” to help identify candidates for testing.

“Testing supplies is a challenge,” Gardner tells the Wisconsin Examiner. “We have the experts, locations and ability to turn results around pretty rapidly, so we can ramp up when supplies are secured. We’re optimistic that soon we’ll be able to match our supplies with the high testing capacity that exists.”

In the meantime, the state continues to work toward further expansion of testing, although it’s not yet able to test everyone.

“There’s a few strategies that we’re trying to understand the true number of infections,” Westergard told the Wisconsin Examiner on Monday, starting with increased testing in healthcare settings — lowering the threshold and testing more people who have symptoms.

“We’ve also started testing asymptomatic people as part of specific outbreak investigations,” he said. When outbreaks occur in nursing homes, jails or other places where people live in close quarters, DHS is expanding testing to include people without symptoms, employing “a blanket approach to testing a large number of people.”

The agency is also studying research on the use of antibody tests as a means of population-wide surveillance for the illness, Westergaard said, “to understand the number of people who’ve been infected and not previously reported to care, or tested in healthcare settings.”

Deaths undetected

When it comes to deaths, the accuracy of data depends on how detailed are the death certificates that doctors, coroners or medical examiners complete — and that can vary.

Tests can be ordered after death as well as before, and medical examiners and coroners around the state have done so. Westergaard said the CDC has shared guidelines with the state on analysis of deaths where COVID-19 has been thought to play a role. Those guidelines have been passed on to local governments and funeral homes, he said, with local governments deciding how to implement them.  

The Dane County Medical Examiner’s office, which also serves Rock, Brown, Door and Oconto counties, has conducted “a limited number” of COVID tests after death, says Barry Irmen, director of operations for the office. “If it’s a natural death what would go on the death certificate, and if it requires a COVID test to rule that in or out, we would do that.”

But neither testing capacity nor the supply of test materials are unlimited, Irmen points out. For that reason, someone who dies without a record of COVID-19 symptoms, or someone who had other serious chronic illnesses that might have contributed to their death, such as high blood pressure or diabetes, might not be tested after death.

While much more widespread testing of the deceased might be ideal for surveillance purposes, “I would also say that if it meant that my loved one had a test while they’re alive, or I had a test after death, I would certainly want the living person to be tested,” he says. But as a result, the COVID-19 death toll is incomplete.

“I completely believe,” Irmen says, “that there are more COVID-related deaths than are being reported.”