Young, otherwise healthy adults most likely can forgo COVID-19 testing, Dr. Brett Giroir, who oversees coronavirus testing for the Trump administration, said Thursday.

"A lot of people are getting tests that probably aren't needed," Giroir said during a "Doc to Doc" interview with NBC News medical correspondent Dr. John Torres, which was streamed on Facebook.

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Even if a person has been exposed to the coronavirus, the advice is to "self-isolate, no matter whether that test is positive or negative," said Giroir, the assistant secretary of health and human services for health.

That's because people who go on to develop COVID-19 may not initially test positive in the days shortly after they've been exposed to the coronavirus. It's possible, therefore, for people to first test negative but then test positive several days later. The incubation period for the illness can be as long as 14 days, according to the Centers for Disease Control and Prevention.

Always make believe that you are infected.

"You should always make believe that you are infected particularly young, healthy people," Giroir said.

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The advice, meant specifically for people without symptoms, appears to be aimed at easing demand for COVID-19 testing, which has led to long delays between getting tested and receiving the results. People who have symptoms of the illness should still get tested, according to the CDC.

Giroir said that 73 percent of test results are ready within three days and that more than 80 percent are ready within five days. That leaves a significant number of people who must wait longer than a week for test results, potentially exposing others in the meantime. Last week, the CDC said self-isolating until test results come back could slow the spread of COVID-19 by up to 86 percent.

Giroir's guidance is meant to "take down the fervor" of testing, he said, even though the country can now handle about 800,000 COVID-19 tests a day.

"We sort of created a frenzy," he said, adding that he has been working with the CDC to issue guidance on testing for otherwise healthy people. It was unclear Thursday when the guidance would be available.

The one exception for young, healthy people, Giroir said, is if they are living with others who are medically vulnerable, such as elderly grandparents.

"In those circumstances, it's much more of a reason to test. But even if you're negative, you need to be really careful around them," Giroir said. "Wear your mask. Keep a safe distance. We can prevent transmission in the household if you do those simple steps."

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Giroir predicted that point-of-care tests, like rapid flu or strep tests, would be readily accessible within the coming month or so.

"By September, we're going to have about 23 million individual point-of-care tests in the market," he said. Most are expected to be in high-risk places, such as nursing homes and schools.

It's also anticipated that such tests would be administered in conjunction with flu tests, using the same samples.

The federal government has ordered extra flu vaccines this year, and it is encouraging everyone to get flu shots, Giroir said. While they're not 100 percent effective in preventing the flu, they can reduce the severity of the illness.

Giroir discouraged people from relying on COVID-19 tests to ease the pandemic, saying tests should be considered "supplemental" only after extensive mask-wearing and physical distancing.

"If you let your guard down, this is a highly infectious disease that will run rampant. As soon as that horse gets out of the barn, it's really hard to put it in."

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Erika Edwards is a health and medical news writer and reporter for NBC News and "TODAY."

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Giroir: The 'worried well' probably don't need COVID-19 tests - NBC News