After weeks of encouraging people to get tested if they may have been exposed to COVID-19, the Centers for Disease Control and Prevention abruptly changed course this week and is now telling the public testing might not be necessary.
The change in guidance, while voluntary, could dramatically decrease the number of tests conducted in the U.S. at a time when public health officials have said they are seriously concerned about young people without symptoms transmitting the virus.
Medical professionals and public health experts swiftly pushed back, calling the move baffling and dangerous because it would reduce the country's visibility on the virus ahead of flu season.
"The people in the trenches are horrified by this," a person who works with the White House coronavirus task force told ABC News Chief White House Correspondent Jonathan Karl. "It gives the impression that asymptomatic people cannot transmit the disease, which is not true. Community spread is driven by asymptomatic people."
The Trump administration's testing coordinator, Adm. Brett Giroir, defended the move as trying to prevent a "false sense of security" that some people have after getting a negative test result.
On a call with reporters Wednesday, Giroir also flatly denied any political involvement in the decision. He said the new testing guidelines came from the CDC with no intervention or direction from President Donald Trump.
"Let me tell you, right up front that the new guidelines are a CDC action," Giroir said.
The new guidance directly contradicts what CDC Director Robert Redfield told ABC News last month: "Anyone who thinks they may be infected -- independent of symptoms -- should get a test."
Redfield's comments came as case numbers in the U.S. were on the rise and health officials worried that younger people -- attending protests and campaign rallies, as well as parties and bars -- were driving the transmission. He issued a new statement agreeing with the rules late Wednesday.
"Everyone who needs a COVID-19 test, can get a test. Everyone who wants a test does not necessarily need a test; the key is to engage the needed public health community in the decision with the appropriate follow-up action," he said, including the italics.
Richard Besser, who served as acting CDC director in 2009, told ABC News that the agency should be "out in front" on explaining the scientific rationale for the change. Besser said he believes the changes are coming from HHS and not CDC.
"Given that a larger number of people who get infected will not have symptoms, it is essential that people who have been exposed are tested," Besser said. "This change in guidance and the way it was released will decrease trust in our nation's public health agency at a time when trust is essential."
Giroir insisted the change comes because it doesn't do much good to have tests done in an area where there is no evidence of spread. A test result also is only valid for the day it's taken.
"Getting a negative test that three days is not totally meaningless, but pretty close to it. It should not give you a self assurance that you will be negative. It should not give you a false sense of security, you should not engage in risky behavior," Giroir said.
He said there were probably 20 drafts of the guidelines in a month and "lots of editing" from other task force doctors, including Dr. Anthony Fauci, the nation's top infectious disease expert; Dr. Deborah Birx, the White House coordinator on coronavirus; Stephen Hahn, head of the U.S. Food and Drug Administration; and Dr. Scott Atlas, a new adviser to the president.
"I worked on them. Dr. Fauci worked on them. Dr. Birx worked on them. Dr. Hahn worked on them. Dr. Atlas provided input. So, it's kind of hard to know how much was written by one person at this time, but it was a CDC product with lots of editing. Lots of input probably over about a month period of time," Giroir said.
At one point, Giroir noted "we all signed off on it, the docs" before political leaders saw it.
Fauci, though, said he did not personally sign off on the new guidance. The revisions were approved during a task force meeting on Aug. 20 -- the same day Fauci was under general anesthesia for surgery to remove a polyp from his vocal cords.
New York Gov. Andrew Cuomo said Wednesday on a conference call with reporters that the reversal from the CDC "strains credulity."
"The only plausible rationale is they want fewer people taking tests," said Cuomo.
The White House and CDC did not answer questions about the change, which was made quietly on the CDC website this week. Questions were referred to Giroir and CDC's parent agency, the Department of Health and Human Services, which is run by Azar, who as a Cabinet secretary reports directly to Trump.
Trump has said he thinks the U.S. conducts too many tests and falsely claimed that testing is what has caused a surge in cases in the U.S. Last June, Trump told supporters in Tulsa, Oklahoma: "When you do testing to that extent, you're going to find more people, you're going to find more cases. So I said to my people, 'Slow the testing down, please.'"
A spokeswoman for the New York City Health Department told ABC News the city would make no change to its testing policies: "We've fought like hell to expand testing without any federal support and we're not slowing down any time soon!"
It's possible that the relaxed guidance will lend cover to other states seeing widespread transmission. While CDC guidelines are voluntary, many local officials use them to insist on people removing themselves from classrooms or work to await testing results. The new rules could be used to allow people, such as teachers, to remain in classrooms even after a known exposure.
In new guidance dated Aug. 24, CDC says that so long as a person doesn't show symptoms testing not necessary.
"You do not necessarily need a test unless you are a vulnerable individual or your health care provider or State or local public health officials recommend you take one," the CDC now states.
Fauci and Giroir told Congress last June that Trump had never asked them to slow down testing efforts. Giroir at the time said he was proceeding in the opposite direction.
"My purpose in leading is to increase the number of testing," Giroir told a House committee on June 23. "The only way we will be able to understand who has the disease, who is infected and can pass it, and to contact tracing, is to test appropriately, smartly, and as many as we can."
The quiet change comes amid questions on whether politics has leaked into public health guidance.
This week, the head of the U.S. Food and Drug Administration, Stephen Hahn, acknowledged that he overstated the benefits of convalescent plasma. With President Donald Trump at his side, he announced he was authorizing the treatment -- frustrating some researchers who say they wanted to continue to conduct placebo-controlled clinical trials to see if it worked.
Trump later bragged that he got the FDA to act, despite the agency's insistence that politics hadn't influenced its decision.
On Wednesday, Hahn said he wanted to work on building trust with the public ahead of the vaccine trial.
"We at FDA recognize that we must build public trust so there is confidence in future decisions about vaccines for #COVID19," he tweeted Wednesday. "I am concerned when I see public surveys that many people will decline taking a vaccine."
ABC News' Aaron Katersky, Libby Cathey and Ben Gittleson contributed to this report.