In a decision that has left many public health experts confused and suspicious, the Centres for Disease Control and Prevention has abruptly changed its testing guidelines for covid-19. According to the agency, people who have likely been exposed to an infected person do not necessarily need to get tested for covid-19 if they’re not experiencing symptoms. Previously, the agency recommended testing for anyone with a known or suspected exposure to the coronavirus.
Scientists have long advocated for vigilant testing of people who may have been exposed to the virus, regardless of whether they feel sick. For one, it’s strongly suspected that people can spread the virus while asymptomatic or shortly before they develop symptoms. So testing, if conducted quickly enough, may be able to identify newly infected people, who could then quarantine. Secondly, a positive test can prompt an investigation by contact tracers, who then may be able to trace the source of an outbreak and stop it from spiraling out of control. This is less feasible in areas of high community transmission, but a lack of testing in the first place can contribute to that happening.
For people who have been in close contact with someone who has covid-19 (regardless of how long the interaction lasted) but aren’t feeling sick, the CDC now advises that they do not necessarily need a test unless they have preexisting health conditions or have been told to get one by their doctor or state and local public health officials. It also discourages people with no symptoms who do not believe that they’ve been exposed to anyone with covid-19 recently from getting tested at all. Beforehand, the CDC recognised the testing of asymptomatic people as an important way to “control transmission.”
Other guidelines still encourage some people to self-isolate for up to two weeks if they suspect they could be infected (if for instance, they’re caregivers of someone with covid-19), but many experts have been sharply critical of the new changes and worry that this will lead to less overall testing.
I can't see any real reason to stop recommending testing asymptomatics, including close contacts of those infected. @US_CDC is sending reporters to @HHSGov, which makes me think that this was a political decision, not a scientific one. 1/ https://t.co/qsh5RIDnC7
— Gregg Gonsalves (@gregggonsalves) August 26, 2020
Tom Frieden, former director of the CDC, said on Twitter Wednesday that the change in testing guidance was inexplicable, “probably indefensible,” and may have been forced upon the CDC; he also criticised another change in recommendation by the CDC, which no longer explicitly calls for travellers returning from overseas or out-of-state to self-isolate for two weeks (both changes appear to have been made on Monday). President Trump has repeatedly downplayed the need for testing and called for it to slow down, suggesting that it only serves to make his administration look bad.
When asked for comment on this guidance change, a CDC spokesperson directed Gizmodo to the press office of the Department of Health and Human Services. HHS has not yet responded to a request for comment. HHS is scheduled to hold a press conference at 2pm ET today to provide an “update on covid-19 testing efforts.” We will update this article with any additional information as we get it.