‘It’s Kitchen Sink Time’: Fast, Less-Accurate Coronavirus Tests May Be Good Enough

For months, the call for coronavirus testing has been led by one resounding refrain: To keep outbreaks under control, doctors and researchers need to deploy the most accurate tests available — ones reliable enough to root out as many infections as possible, even in the absence of symptoms.

That’s long been the dogma of infectious disease diagnostics, experts say, since it helps ensure that cases won’t be missed. During this pandemic, that has meant relying heavily on PCR testing, an extremely accurate but time- and labor-intensive method that requires samples to be processed at laboratories.

But as the virus continues its rampage across the country and tests remain in short supply in many regions, researchers and public health experts have grown increasingly vocal about revising this long-held credo. The best chance to rein in the sprawling outbreaks in the United States now, experts say, requires widespread adoption of less accurate tests, as long as they’re administered quickly and often enough.

“Even if you miss somebody on Day 1,” said Omai Garner, director of clinical microbiology in the U.C.L.A. Health System. “If you test them repeatedly, the argument is, you’ll catch them the next time around.”

This quantity-over-quality strategy has its downsides, and is contingent on an enormous supply of testing kits. But many experts believe more rapid, frequent testing would identify those who need immediate medical care — and perhaps even pinpoint those at greatest risk of spreading the disease.

Such a considerable shift would likely be a welcome change for a country where the status quo of testing was just described as “unacceptable, period” by Dr. Anthony Fauci, the director of the National Institute of Allergy and Infectious Diseases, in an interview Wednesday on CNN.

“If you had asked me this a couple months ago, I would have said we just need to be doing the PCR tests,” said Susan Butler-Wu, a clinical microbiologist at the University of Southern California. “But we are so far gone in this country. It is a catastrophe. It’s kitchen sink time, even if the tests are imperfect.”

Of the dozens of coronavirus tests that have been granted emergency use authorization by the Food and Drug Administration, most rely on complex laboratory procedures, like PCR, to detect the coronavirus’s genetic material.

Only a handful are quick and simple enough to be run in what is called a point-of-care setting, like a doctor’s office or urgent care clinic, without the need for lab equipment. And these tests are still relatively scarce nationwide. Government officials have pledged to astronomically scale up the number of point-of-care tests by fall, increasing by millions the weekly tally of tests conducted.

But many of the rapid tests at the center of this buzz still rely on specialized machines that are neither cheap nor easy to produce in bulk. And while some rapid tests, like the Abbott ID Now, were quickly adopted into the White House, most are unlikely to get much play in the larger community.

“We can’t have these in every household,” said Michael Mina, an epidemiologist at Harvard University’s School of Public Health and a

Frequently Asked Questions

Updated August 6, 2020

  • Why are bars linked to outbreaks?

    • Think about a bar. Alcohol is flowing. It can be loud, but it’s definitely intimate, and you often need to lean in close to hear your friend. And strangers have way, way fewer reservations about coming up to people in a bar. That’s sort of the point of a bar. Feeling good and close to strangers. It’s no surprise, then, that bars have been linked to outbreaks in several states. Louisiana health officials have tied at least 100 coronavirus cases to bars in the Tigerland nightlife district in Baton Rouge. Minnesota has traced 328 recent cases to bars across the state. In Idaho, health officials shut down bars in Ada County after reporting clusters of infections among young adults who had visited several bars in downtown Boise. Governors in California, Texas and Arizona, where coronavirus cases are soaring, have ordered hundreds of newly reopened bars to shut down. Less than two weeks after Colorado’s bars reopened at limited capacity, Gov. Jared Polis ordered them to close.
  • I have antibodies. Am I now immune?

    • As of right now, that seems likely, for at least several months. There have been frightening accounts of people suffering what seems to be a second bout of Covid-19. But experts say these patients may have a drawn-out course of infection, with the virus taking a slow toll weeks to months after initial exposure. People infected with the coronavirus typically produce immune molecules called antibodies, which are protective proteins made in response to an infection. These antibodies may last in the body only two to three months, which may seem worrisome, but that’s perfectly normal after an acute infection subsides, said Dr. Michael Mina, an immunologist at Harvard University. It may be possible to get the coronavirus again, but it’s highly unlikely that it would be possible in a short window of time from initial infection or make people sicker the second time.
  • I’m a small-business owner. Can I get relief?

    • The stimulus bills enacted in March offer help for the millions of American small businesses. Those eligible for aid are businesses and nonprofit organizations with fewer than 500 workers, including sole proprietorships, independent contractors and freelancers. Some larger companies in some industries are also eligible. The help being offered, which is being managed by the Small Business Administration, includes the Paycheck Protection Program and the Economic Injury Disaster Loan program. But lots of folks have not yet seen payouts. Even those who have received help are confused: The rules are draconian, and some are stuck sitting on money they don’t know how to use. Many small-business owners are getting less than they expected or not hearing anything at all.
  • What are my rights if I am worried about going back to work?

  • What is school going to look like in September?

    • It is unlikely that many schools will return to a normal schedule this fall, requiring the grind of online learning, makeshift child care and stunted workdays to continue. California’s two largest public school districts — Los Angeles and San Diego — said on July 13, that instruction will be remote-only in the fall, citing concerns that surging coronavirus infections in their areas pose too dire a risk for students and teachers. Together, the two districts enroll some 825,000 students. They are the largest in the country so far to abandon plans for even a partial physical return to classrooms when they reopen in August. For other districts, the solution won’t be an all-or-nothing approach. Many systems, including the nation’s largest, New York City, are devising hybrid plans that involve spending some days in classrooms and other days online. There’s no national policy on this yet, so check with your municipal school system regularly to see what is happening in your community.

Researchers don’t yet know how much virus a person needs to carry in their body to actually transmit it. But the range in which the accuracy of antigen tests starts to drop off is probably far below that level, Dr. Mina said.

Testing frequency can also be a formidable foe to disease transmission. In a recent paper that has yet to be published in a peer-reviewed scientific journal, he and Dr. Larremore showed through mathematical models that a relatively insensitive test, rolled out twice a week, vastly outperformed a more accurate test, administered once every two weeks, in curbing the spread of disease. Other studies pitting speed against sensitivity have come to similar conclusions.

The upshot here is a practical one, Dr. Garner said. “You’re not trying to find every single person who has the virus,” he said. “You’re trying to mitigate outbreaks.”

That approach is a substantial departure from the way that many lab researchers have traditionally tackled infectious disease testing.

“We’re in sort of a new era of testing,” said Esther Babady, a clinical microbiologist at Memorial Sloan Kettering Cancer Center. “Usually we use tests to diagnose disease states in patients, not look for disease states. Now, with Covid, we are starting to look for this virus everywhere.”

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Credit…Joe Raedle/Getty Images

A testing rethink this substantial will inevitably come with snags. The success of the speedy testing strategy hinges heavily on availability — something the United States has utterly failed at since the virus first made landfall within its borders. Ramping up antigen testing may only add strain to an already sputtering supply chain, potentially hampering plans for widespread use.

“If you test people all the time, you can account for lack of sensitivity,” Dr. Butler-Wu said. “But are you really going to test people all the time? If the answer is no, then that lack of sensitivity becomes more of a big deal.”

And many experts are still hesitant to trust negative antigen results, which may need to be backed up with a more sensitive test. That might not be very burdensome in the midst of an outbreak, when positivity rates are likely to be high, Dr. Babady said. In spots where infection rates are especially low, however, “that is not going to be the best approach to testing,” she said.

Cheap tests also aren’t the same thing as free tests. Even $1 tests can start to rack up quite a bill, especially for large families hoping to do daily checkups or nursing home aides required to get tested repeatedly. Left unregulated, the testing market could end up exacerbating the socioeconomic split that’s already disproportionately burdened some sectors of the population with the worst effects of Covid-19.

Concerns over accuracy bogged down the approval process for simple, speedy tests. F.D.A. guidelines stipulate that any new coronavirus test vying for emergency clearance from the agency must perform nearly as well as the gold standard of PCR.

The F.D.A.’s rules frustrate Dr. Mina, who noted that several companies on the verge of debuting antigen tests have found the regulatory hurdles daunting. “Many of them are not even bothering,” he said. “‘Our product might not be good enough. So what’s the point?’”

That’s left the onus on the few companies who already have the F.D.A.’s green light. In hopes of encouraging a speedier, ramped up production, the governors of seven states announced this week a joint bid to purchase a total of 3.5 million antigen tests from BD and Quidel.

There probably isn’t one way to grapple with all these issues — and certainly not an obvious one, Dr. Butler-Wu said. What’s clear to her and others, though, is that the current situation is untenable.

“Our backs are against the wall, and it’s Hail Mary time,” Dr. Butler-Wu said. “We have to try something different.”


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Author: Katherine J. Wu
August 8, 2020