Originally Published: 01 MAR 22 07:55 ET

Updated: 01 MAR 22 07:56 ET

By Amanda Sealy and Deidre McPhillips, CNN

(CNN) -- As the United States emerges from the Omicron wave, Covid-19 testing has slowed to a fraction of what it was at the beginning of the year.

In mid-January, as daily case counts reached their peak, about 2.5 million tests were processed each day in the United States. Now, there are about 670,000 tests coming through each day, according to data from the US Department of Health and Human Services.

The federal data tracks results submitted by more than 1,000 laboratories and testing locations across the country but doesn't capture the vast majority of at-home tests that have grown in popularity as supply became more readily available.

But demand seems to have fallen there, too. One major retailer, CVS, has seen a decline in demand for home tests since the Omicron peak, according to a company spokesperson.

And out of the long-awaited 500 million free at-home Covid-19 tests the Biden administration has made available, fewer than 300 million have been ordered, according to Kevin Munoz, White House assistant press secretary.

Reasons for this decline are two-fold, according to Mara Aspinall, a professor of practice in biomedical diagnostics at Arizona State University. On one hand, cases are coming down, and on the other, demand is simply starting to fade.

Cases are down more than 90% since the peak of the pandemic, but the US is just starting to drop to pre-Omicron case rates, and that's why Aspinall and other experts warn of the need to take this opportunity to make sure the country is better prepared for surges.

"When you look at epidemics and pandemics in the past, the countries and communities that performed best are ones that were most flexible and were able to respond to existing demand," Aspinall said.

Too little, too late

"Part of the ongoing challenge of the pandemic has been the difficulty in ramping up testing as a surge is beginning, and unfortunately, time and time again, our testing efforts have been hampered by too little, too late," said Dr. Thomas Tsai, an assistant professor at the Harvard T.H. Chan School of Public Health.

Even as tests seem more accessible now, it was just two months ago that the Omicron variant -- paired with the holiday season -- left Americans with long lines for testing sites and empty drugstore shelves.

Of the 22 million at-home tests sold last year at CVS, 70% were sold in the final three months of the year, according to a company spokesperson.

Throughout the pandemic, there have been warning signs that testing supplies would be strained.

During last year's Delta surge, testing rose quickly starting in July and held for months at levels previously seen during the first winter surge. One of the largest at-home test manufacturers, Abbott Laboratories, warned that there could be a shortage of supplies.

In September, the Biden administration announced that it would invest $2 billion in testing, and it added another billion in purchase agreements in October. However, that was only enough to provide the US with about 200 million at-home tests a month.

In October, Aspinal told CNN that these investments were a "significant step forward." But she added, "in order to use testing to eliminate onward transmission, the numbers are closer to testing at least 6 million a day."

The arrival of Omicron continued to re-emphasized the importance of the White House's efforts to remedy its testing shortage, including the distribution of those 500 million free at-home tests. But now, demand is going down.

"Certainly, the supply has increased just as the demand has started to level out or reduce, as the recent Omicron wave and COVID-related cases associated with it drop lower. This has created an availability of tests that were not available when we needed them most, during the holidays," epidemiologist Dr. Michael Mina said.

Testing is still relevant

"Testing, especially as the Omicron wave goes down, does not lose its relevance," Mina emphasized. "Testing is how we see the virus. We can't see it if we do not test."

Sick people will be "in the dark" about whether their symptoms are from Covid-19, influenza or a cold, he said, so it's key to have rapid antigen tests on hand before visiting with people who are vulnerable or when making decisions about whether to wear a mask or stay home from work.

The US Centers of Disease Control and Prevention recommends Covid-19 testing:

If you have Covid-19 symptoms

If you have known or suspected close contact with the coronavirus Before or after travel

For screening in schools, workplaces, etc.

When asked by a health care professional or public health official

Most important, Mina said, is that access to testing is "absolutely crucial to get treatment fast."

Both Pfizer's and Merck's Covid-19 antiviral treatments should be started within a few days of the start of symptoms, and since they require a prescription, this requires confirmation via a Covid-19 test.

Right now, the timeline for when people can get a positive test result and see a doctor to start these treatments can put them out of the "therapeutically beneficial time frame," says Mina, who is also the chief science officer for the telehealth company eMed. The company's "Test-to-Treat" program immediately links someone who tests positive at home to treatment options.

"If we can stop hospitalizations, then even if cases increase again, the importance that the virus holds over us is greatly reduced," he said.

Continuing the momentum

During a White House Covid-19 briefing last month, Dr. Tom Inglesby, senior adviser to the White House on coronavirus response, acknowledged that demand for tests will wane as cases decline but announced a plan to help sustain testing momentum. Officials have sent a formal request to the testing industry for proposals on how to face market volatility and supply chain struggles, as well as ideas about how to scale up manufacturing.

Test manufacturers Quidel, Roche and Abbott, which all have contracts with the US government, told CNN that they are committed to providing tests for Americans.

Abbott alone is "scaling toward producing 100 million tests a month in March," according to spokesperson John Koval.

However, Mina said these manufacturers still need financial incentives, especially when demand is down.

"The administration should provide guaranteed purchases to manufacturers so that they can scale their operations without fear that sales will slump. This happened last year and is part of what led to the testing crisis this winter," he said.

Tsai agrees that this kind of commitment is necessary and that a supply of tests should be kept in the Strategic National Stockpile, along with "clear plans for distribution to both hotspots and nationally."

"I think it will be challenging for testing manufacturers to continue producing a supply of tests without a clear market signal of ongoing demand. Rapid antigen tests need to be considered a public good," Tsai added.

Getting comfortable with testing

The White House continues to emphasize that there are 20,000 free Covid-19 testing sites across the country, but one silver lining of the recent surge might be that Americans are more comfortable with testing at home.

"I believe most people learn from experience. And you say the test works and it's easy to use, which is good, but until you've actually done it yourself, until you've actually seen that it is as easy as they say or it's as fast as they say or it's as less painful as they say, I think a lot of people are not comfortable with just jumping in. And having done something once, it's a whole lot easier," Aspinall said.

Aspinall also points out that due to free testing and access to at-home tests, many barriers to testing have finally been removed.

With increased education, access and now supply, Tsai also sees this as an important moment for the future of rapid antigen testing.

"I'm encouraged that the Omicron wave has engendered a paradigm shift in the role of rapid antigen tests, and hopefully the lessons of the Omicron wave on the vital role of testing as an early warning system is not lost for future outbreaks."