Trump told a rally in June testing is a "double-edged" sword because it leads to more cases being discovered, causing the United States to appear worse off than it would otherwise. He added that he urged officials to "slow the testing down, please." A White House official at the time told Reuters that the remark was a joke.

The United States has had more than 5 million diagnosed cases of COVID-19 and nearly 180,000 people have died.

California on Wednesday announced a deal with PerkinElmer to nearly double the state's testing capacity, and New York Governor Andrew Cuomo quickly challenged the assertion that politics played no role in the change.

“We need public health people who do public health and not politics, and we’re going to disregard the CDC guidance totally,” he told MSNBC.

Tests of asymptomatic people conducted too early to accurately detect the virus can lead to a false sense of security and potentially help spread the virus, Giroir said.

Health experts said the move could hurt contact tracing efforts to prevent virus spread.

“It’s inexplicable why this guidance suddenly changed. There is no new science that we’re aware of," Dr. Leana Wen, former Baltimore health commissioner and visiting professor at George Washington University Milken Institute School of Public Health told CNN. "We need far more testing, not less."

(Additional reporting by Caroline Humer and Peter Henderson; Editing by Bill Berkrot, Alistair Bell and Tom Brown)