Without explanation, and in contravention of common sense, federal officials have issued new guidance against testing asymptomatic individuals — specifically, those who have been exposed to someone diagnosed with covid-19. The recommendations, issued without fanfare on Monday by the Centers for Disease Control and Prevention, pose a danger to public health, and contradict what we know about how to stem the spread of the pandemic.

The numbers tell the story. The CDC itself estimates that 40 percent of people with covid-19 don’t have symptoms. They are capable of spreading the disease, even if not quite as effectively as those with symptoms; again, according to the CDC, the chance that an asymptomatic individual will infect another person is 75 percent of that of someone with symptoms. Due largely to insufficient testing of asymptomatic individuals, CDC Director Robert Redfield has estimated that the number of people with covid-19 is as many as 10 times higher than the official count.

In other words, we should be testing more people without symptoms, not fewer.

Virtually every public health expert agrees that picking up on these asymptomatic cases is key to controlling the virus. There is a well-established algorithm for containing this and other infectious diseases: find infected individuals, identify their contacts, and put those with the infection and their potentially infected contacts into isolation and quarantine. Testing is key for a disease such as covid-19, for which so many people do not show symptoms, and numerous super-spreader events have been traced back to asymptomatic individuals. I’ve argued that we need to be aiming for millions of tests per day for people going to work and school — and that’s for people with no known exposure.

But you don’t have to be a public health expert to know the CDC’s guidance is nonsensical. Imagine learning that a co-worker with whom you were in close contact was diagnosed with covid-19. You’d want to be tested, because if you were positive, you could isolate from others in your household and avoid transmitting the virus to your family. Your contacts should also be told, too, so they could be tested themselves.

The CDC language contains a hint about a possible rebuttal. It says that “a negative test does not mean you will not develop an infection from the close contact or contract an infection at a later time.” That’s true — a negative test is not a guarantee that you won’t become positive later. That doesn’t mean you shouldn’t be tested. If the problem is that it might be too early on in the incubation period for a test to be positive, the CDC could suggest that another test be done in a few days’ time if the first one is negative. And sure, you can contract the virus through another source in the future. That actually leads to the opposite conclusion: It underscores my point about the need for regular, widespread testing.

The Department of Health and Human Services, which oversees the CDC, has responded to criticism by noting that the guidance still permits testing if it is recommended by a health-care provider or by state or local health officials. This has things completely backward. As a doctor and former local health official, I can tell you that we depend on the CDC for guidance. A change like this leads to confusion. It could cause people not to seek the care they need, and providers and testing sites to turn away patients who could be contagious to others. It could also be an excuse for insurers to refuse to pay for testing.

I worry that this CDC change is part of a larger pattern of diluting recommendations when the federal government can’t do its job properly. On Aug. 3, the CDC changed its guidance on testing to say that those recovering from covid-19 don’t need to be retested. On Aug. 18, the Department of Homeland Security altered its designation of essential workers to include teachers, implying that teachers who were exposed to covid-19 and don’t yet show symptoms don’t need to be tested or to quarantine.

One has to wonder whether these changes were made because the federal government knows it is still falling short on testing, and instead of working to increase availability, officials revised the guidance to justify why more testing isn’t needed.

It isn’t far-fetched to think this. Let’s not forget that when the CDC first released its guidelines on school reopening, President Trump criticized them as too strict, after which the CDC issued revised guidance. Then there’s the Food and Drug Administration appearing to cave to political pressure in authorizing emergency use of plasma therapy — even though just a few days prior, top experts including Anthony S. Fauci, director of the National Institute of Allergy and Infectious Diseases, had concluded there was insufficient basis for taking that step.

The United States has failed in our response to covid-19. This latest move seems to offer yet another example of putting political expediency over solid science. If it is not rethought, at the very least it should be explained.

Even as the number of U.S. coronavirus cases passes 3 million, President Trump has repeatedly played down covid-19’s toll on the country. (The Washington Post)

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