The president has said the U.S. will send half a billion free at-home tests to Americans, but he hasn’t given a timeline for when those tests will be readily available.

Meeting President Joe Biden’s goal of offering 500 million free at-home Covid-19 tests for Americans will require a massive scale-up in test manufacturing that may take months to achieve — falling short of demand as the omicron variant drives a surge in infections.

The U.S. had a supply of around 200 million at-home rapid tests in December. Test-makers have indicated they will be able to increase that to just over 500 million a month by March with added capacity from current manufacturers and the recent clearance of two new tests from Roche and Siemens, according to estimates from Mara Aspinall, a health professor at Arizona State University who tracks the testing market.

Not all of those tests will go to the federal government’s free testing effort. A White House official said the 500 million free at-home tests will come from additional supply the administration is anticipating will be added.

But even with new tests being approved and manufacturers racing to expand capacity, the number of new tests available is expected to grow just modestly in January while Roche and Siemens begin packaging and shipping their products, ramping up more significantly in February. That means it could take several months for the federal government to meet its goal, according to production targets from the manufacturers and Aspinall’s estimates.

“I am much more confident than I was a week ago that we can meet the need,” Aspinall said. “The challenge is how quickly we can get those tests shipped out and how quickly we can meet that 500 million goal.”

Administration officials haven’t said when they expect to have all 500 million tests available for the public, beyond saying the first batch of tests will start going out sometime in January. Officials with the Defense Department and Department of Health and Human Services are aiming to finalize contracts with test manufacturing companies late next week and are working on an “accelerated contracting timeline,” White House Covid response coordinator Jeffrey Zients said Wednesday. Officials are also still working on the website where people will be able to request a test and a system for distributing them, he said.

It also remains unclear how the tests will be distributed, which agency will be tasked with that process and how many tests each person will be able to get.

“There are a lot of unanswered questions,” Aspinall said. “It’s the combination of understanding the supplying pathways, then on top of that figuring out what the supply chain looks like, what the distribution looks like and how the whole process comes together.”

Biden has made testing a priority for this administration in recent months, committing to spend $3 billion in the fall on at-home tests to spur companies to scale up production as the government distributes millions of at-home tests to food banks and health clinics. Administration officials have urged Americans to get tested before holiday gatherings as an added layer of protection and enforced testing programs in schools to keep children in the classroom.

Even before Biden announced his plan for the federal government to buy 500 million tests, representatives for test manufacturers had been pushing to ramp up production further, hiring more workers, adding shifts and tapping subcontractors to help, with production going from 80 million tests in November to just over 200 million in December.

Abbott, maker of BinaxNow, said it plans to increase capacity to 70 million tests per month from 50 million, and Quidel is increasing its production of the QuickVue test to the same amount. Access Bio said it was targeting 25 million tests for December and planned to produce an additional 40 million in the coming months. Ellume said it will start making 15 million more tests a month after production launches at its new facility in Frederick, Maryland, in January.Meh

The Food and Drug Administration also gave clearance in the last week to new tests from Roche and Siemens, with each company saying the plan is to have “tens of millions” of the new tests available each month, without offering a specific timeline for how many tests would be delivered when.

Having the federal government ready to purchase such a large amount of tests could give the test-makers an incentive to ramp up production even further than planned, though demand from consumers and local governments for the tests has already outstripped the available supply, Aspinall said.

While the federal push is helping bolster the market for manufacturers, it has also raised questions about what effect it could have on the wider availability of tests. Arkansas Gov. Asa Hutchinson told Biden earlier this week on a call that he was worried his state won’t have enough of the rapid tests for its test-to-stay program for schools, where students exposed to an infected classmate are able to remain in class if they test negative.

The Association of State and Territorial Health Officials raised a similar concern to Biden administration officials, questioning whether the federal government’s massive purchasing of tests might cut into their ability to access tests for their own programs. Michael Fraser, the group’s CEO, said administration officials assured him that the federal government’s efforts won’t hinder states’ plans.

Also competing for tests will be employers and their workers, if Biden’s vaccine mandate survives legal challenges. Under that rule, unvaccinated employees would have to show proof of a negative Covid test every week.

Hutchinson warned Biden that the administration should not “let federal solutions stand in the way of state solutions.”

“The production of 500 million rapid tests that will be distributed by the federal government is great,” the Arkansas Republican said, “but obviously that dries up the supply chain for the solutions that we might offer as governors.”