There are some pleas for caution on at-home tests, even among their boosters. Topol, from the Scripps Research Translational Institute, argues that we first need a large clinical trial to show that the tests are effective at stopping outbreaks. The test that does so, then, could set the standard for others like it.
Other experts say that imprecise, at-home tests are a terrible idea. Michael Osterholm, the director of the Center for Infectious Disease Research and Policy at the University of Minnesota, worries that if the country is awash in tests that return too many incorrect results, people will lose confidence in testing. They might refuse to get tested, refuse to self-isolate if they test positive, or get PCR and antigen tests mixed up. After the federal government gave nursing homes some antigen rapid tests, the state of Nevada ordered the homes to stop using them once they were found to have an error rate of nearly 60 percent. Another rapid test made by the company Quidel was found to detect only 32 percent of the positive cases identified by a PCR test. (Part of the explanation for the delayed development of cheap, at-home testing might be the mixed messages experts are sending on the effectiveness of at-home tests.)
Osterholm and others are concerned that if people start testing at home, positive cases might not be reported back to public-health departments. Advocates of at-home tests say they should come with apps that people can use to report their results anonymously to their local health department.
The point of rapid testing is not to stop all cases, proponents argue, but to reduce how many there are. People would still have to take precautions, but they would have an extra measure of security knowing they are (likely) not contagious.
What’s more, different types of tests could be used in tandem. A positive antigen test could be confirmed with a PCR test, or one antigen test could confirm a different kind of antigen test. (This type of confirmation is similar to what happens with positive HIV antibody tests.) “We don’t have enough money to do PCR in everybody, every day,” says Mara Aspinall, a biomedical-diagnostics professor at Arizona State University. In the case of a positive antigen test at a nursing home, for example, “if you have to send a nurse home for a day, before you get a central-lab PCR test, it’s a small price to pay. It’s not ideal; it’s logistically a hassle. But it’s a lot cheaper than an outbreak.”
Besides, right now, we’re keeping everyone home because we don’t even know who might have the coronavirus. There is no “perfect,” these experts argue, and the alternative is bad. “Knowing more is better than knowing less,” says Paul Romer, a Nobel Prize–winning economist and an advocate for this kind of testing.
To help people understand the risks of false positives and negatives, Mina said, the U.S. needs a major public-education initiative paired with the tests. People should be told what their results mean, and how to incorporate them into their already-careful lifestyles. “The NIH and the CDC should be hiring, for whatever cost it takes, Coca-Cola’s branding team,” to show people how to use the tests, Mina said.