Governors of some states, including New Jersey and Connecticut, announced on Twitter just before Mr. Trump’s news conference that they expected to receive thousands of the tests within coming weeks, and millions by year’s end.
Some 6.5 million of those tests would ship this week, said Admiral Giroir, adding that they could be used in settings such as doctor’s offices or pharmacies.
“This is, it was said by Republicans and Democrats alike earlier, this is a game changer,” Gov. Tate Reeves of Mississippi, a Republican, said at the White House news conference, adding that the kits would allow teachers in his state to be tested “every single day.”
The tests, which the Food and Drug Administration gave an emergency greenlight in August, are cleared only for use in people with symptoms of Covid-19 and must be administered by, or in the presence of, a trained health care professional. Such tests are intended for use, according to Abbott, within the first seven days of when a person starts to feel ill.
When the company sought approval, it did not demonstrate that its rapid tests were effective in people who don’t have symptoms, what is considered by the F.DA. to be an off-label use. But comments like Mr. Reeves’s suggested they might be used for screening or surveillance of people without symptoms in some locations.
“We don’t know anything about these tests’ efficacy in asymptomatic patients,” said Dr. Krutika Kuppalli, an infectious disease physician at the Medical University of South Carolina. “We need to be using tests that have been validated in their performance.”
The test is also designed to look for antigens, or pieces of coronavirus proteins. Such tests tend to be less accurate than laboratory tests, most of which rely on a time-intensive but very reliable technique called PCR.