The federal government appears to have backtracked on COVID-19 testing guidance, according to a statement released late Wednesday from the director of the Centers for Disease Control and Prevention.
Disputed recommendations posted to the CDC website on Monday suggested people exposed to the coronavirus "do not necessarily need a test" unless they're having symptoms, are older or are otherwise medically vulnerable.
Full coverage of the coronavirus outbreak
In the new statement, the CDC's director, Dr. Robert Redfield, now says that "all close contacts of confirmed or probable COVID-19 patients" may consider testing.
"Dr. Redfield appears to have walked back from that a little bit," said Dr. William Schaffner, an infectious disease expert at Vanderbilt University Medical Center in Nashville.
Despite Redfield's statement, the CDC's website had not changed as of Thursday afternoon.
"I think this is a black eye for the CDC. They've got materials on their website that really can't be scientifically justified," said former CDC director Dr. Tom Frieden, who is now president of Resolve to Save Lives, a global public health initiative.
The recommendation from the CDC — which reversed previous advice that anyone exposed to COVID-19 should be tested, even if they weren't symptomatic — was met with backlash.
The White House Coronavirus Task Force finalized the change to the testing guidance one week ago, the day one of its members, Dr. Anthony Fauci, was having surgery.
On Wednesday, a spokesperson from the National Institute of Allergy and Infectious Disease, which Fauci leads, said that Fauci recalled "quickly reviewing a version of the guidelines" that had circulated previously.
"At the time he was not struck by the potential implications of this particular change in the version he reviewed," the spokesperson said. "Now reading them carefully, he has some concern that the revised guidelines could be interpreted as lessening the importance of asymptomatic spread of virus in the community."
Redfield said the CDC's latest guidance was an attempt to place "an emphasis on testing individuals with symptomatic illness."
Testing people who've been in contact with COVID-19 patients is a classic, tried-and-true method of infectious disease control. That includes infected people who don't feel sick.
"The biggest Achilles' heel of the disease is that about 40 percent of people out there who get infected with this virus are asymptomatic or mildly symptomatic," Dr. Carlos Del Rio, executive associate dean at Emory University School of Medicine in Atlanta. "If they're still transmitting it and we don't know who they are, we're going to be in trouble."
"Everyone who needs a COVID-19 test, can get a test," Redfield said. "Everyone who wants a test does not necessarily need a test."
The CDC does not mandate which people can or should be tested for the coronavirus. Those decisions are left to local and state health authorities, and are dependent, in some cases, on the availability of tests.
Download the NBC News app for full coverage of the coronavirus outbreak
A joint statement from the governors of Connecticut, New Jersey and New York called the new testing guidelines "reckless," and said the states would "continue to follow the advice of health experts to contain and prevent the spread of COVID-19, and therefore will not be changing our guidance that prioritizes testing" for asymptomatic individuals.
The incubation period for COVID-19 is considered to be 14 days, meaning a person might become infectious and/or develop symptoms within two weeks after exposure.
Therefore, it is possible, in some cases, to be tested too early. For example, a negative result on day four after an exposure could become a positive result on day 10.
That's why the CDC and many public health experts advise anyone who has been exposed to the virus to quarantine for those two weeks, taking extra precautions, such as physical distancing and wearing a mask.
"Asymptomatic spread is a reason behind the universal mask guidance," Schaffner said. "Here I am feeling great, but I cannot assure you that I'm infection free, and you cannot assure me that you're infection free. We better wear masks."
Follow NBC HEALTH on Twitter & Facebook.