• Fast, at-home COVID-19 tests coming to U.S. this year,

WASHINGTON — The White House announced Monday it is buying 8.5 million rapid coronavirus tests that can be taken at home without a prescription and that yield immediate results.

The $231.8 million contract will allow Australian company Ellume, which manufactures the tests, to quickly scale up its production and create a manufacturing facility in the United States. Once running, that factory will be able to produce 19 million tests per month.

For the past year, many experts have called for the development of cheap, rapid home tests as a way to catch and stop viral transmission. Because so much of the transmission occurs among people showing no symptoms, giving Americans an inexpensive way to test themselves regularly would be a breakthrough. But even as testing technology improved, the cost and availability of such tests lagged and remained prohibitive.

Ellume’s home coronavirus test was the first overthe-counter, rapid coronavirus home test to be authorized by the Food and Drug Administration; it was approved Dec. 15. But the test was expected to be available only in limited quantities.

“The purpose of today’s announcement is to move to mass production and scale,” said Andy Slavitt, President Joe Biden’s senior adviser for COVID-19 response, at a Monday news briefing.

Mr. Slavitt acknowledged that the $30 price per Ellume test — while cheaper than many of the $100-$200 tests that need to be processed by a lab — is still too high for it to be used ubiquitously by many people.

“The cost will come down only if we get to that mass production and scale,” Mr. Slavitt said, calling the new contract an initial step to solve that problem. “We know there are efforts to create even lower cost and more innovative approaches and we welcome those.”

In an interview with The Washington Post, Ellume founder and CEO Sean Parsons said he believes scaling up production will allow Ellume to reduce the test’s price. By building a manufacturing plant in the U.S., for instance, the company will no longer have to ship tests from Australia.

The tests could be vital tools in the country’s fight against the virus — especially in the months before most Americans are vaccinated. Unlike previous home tests, the Ellume test does not require samples to be sent to a lab and can be taken without doctor’s orders by anyone older than 2. Two other home tests approved by the FDA — Lucira Health’s “All-In-One” test kit and Abbott’s BinaxNOW test — require a doctor’s prescription, making them unhelpful for stopping asymptomatic transmission.

But the U.S. will have few tests before many Americans are vaccinated. Under the new contract, Ellume is expecting to ship 100,000 tests to the United States per month from February to July.