Test Everyone for Coronavirus? We're Not There Yet

Test Everyone for Coronavirus? We're Not There Yet

(Bloomberg Opinion) -- The White House is investigating “self-swab” coronavirus tests, President Trump said Wednesday, implying that a do-it-yourself test for Covid-19 might be imminent. Soon, maybe all of us can just swab our own throats and find out if we’re infected.

That might seem like good news, for everyone knows testing has been a weak spot in the American response to the pandemic. And many people would like to know if they’ve been exposed to the virus, if only to avoid infecting the most defenseless people in their lives.

But, in fact, Trump’s announcement suggests he does not understand what tests are needed in the U.S. – and who actually needs them. The danger is that this will add to public misunderstanding about testing. The U.S. is terribly behind in testing, it’s true. As my Bloomberg Opinion colleague Faye Flam points out, much more testing is needed to stem the tide of Covid-19. After government missteps in creating and approving Covid-19 tests, we’re still scrambling to come up with the millions of tests needed to find out how far the disease has spread in the U.S.

Getting this picture, however, and helping the people suffering from Covid-19 recover, does not call for testing everyone. What’s needed – and what must be a priority – is getting tests for the people who are ill or who at least have symptoms and are in a vulnerable category: they’re over 65, have underlying medical conditions or are health-care workers. And we barely have enough tests for them.

Note that scarcity exists not only for tests but also for the masks that health-care workers need when administering them (and when treating ill patients) and for the materials such as enzymes and reagents that laboratories need in processing them. Every non-essential test that’s given depletes these other resources and makes it harder to provide the most urgent health care.

In any case, testing the worried well cannot provide the security they seek. Someone who tests negative today could turn out to be infected tomorrow – due to later exposure or to a false test result. Existing tests for Covid-19 are not 100% accurate. Even if a test is conducted perfectly, meaning that a good, clean specimen is collected, it may not detect viral DNA in someone who has just been infected. So it’s impossible to be certain that you are disease-free and therefore incapable of infecting Grandma. (In the U.S., an FDA-approved antibody test that can tell whether a person has been exposed to the coronavirus has yet to enter the market.)

If the U.S. can build up supplies sufficient to test everyone who is very ill – still a reach, given the backlog – or, even harder, every vulnerable person with symptoms, it will help provide a clearer picture of U.S. outbreak. In the meantime, promoting do-it-yourself tests and seeking to test everyone only amplifies confusion. It adds nothing to the basic advice everyone, whether you’ve been tested or not, needs to follow: Avoid unnecessary contact with others, especially those at greatest risk.

This column does not necessarily reflect the opinion of Bloomberg LP and its owners.

Mary Duenwald writes editorials on energy, health care and science for Bloomberg Opinion. She was deputy editor of the New York Times op-ed page and a senior editor at Harper’s Bazaar, Real Simple, the Sciences and Vogue.

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