At-home coronavirus test kits are still not in the hands of consumers. Here's why.

As government and health care officials plead for expanded access to high-speed COVID-19 tests, health care companies across the country began mobilizing their resources to meet the growing demands with direct-to-consumer kits.

The benefits of such kits could be substantial, allowing everyday people to test themselves for COVID-19 in the privacy of their homes instead of visiting a hospital, potentially exposing health care workers and other healthy individuals. If the test came back negative, it could allow them to go back to work without fear of infecting others.

But the path to commercialization has been a bumpy one. On March 16, the Food and Drug Administration issued new, loosened guidelines meant to help accelerate the availability of different types of COVID-19 diagnostic tests. Under the new policy, laboratories approved by the Centers for Medicare and Medicaid Services under the Clinical Laboratory Improvement Amendments (CLIA) were allowed to manufacture and distribute a validated COVID-19 test for 15 days before submitting official Emergency Use Authorization from the FDA.

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Gail Javitt, director of the Hyman Phelps and McNamara Center, told ABC News that the FDA's relaxed rules were not intended to last forever.

"Emergency use authorization is not approval," she said. "Once an emergency is over, distribution has to cease."

Nevertheless, the relaxed regulatory process effectively gave companies and independent laboratories the green light to start scaling up small COVID-19 testing kits to be shipped to individual homes.

Several companies, such as Everlywell and Nurx, had already started distributing their at-home kits when the FDA issued a surprise notice on March 20.

In that note, the FDA said it had "not authorized any test that is available to purchase for testing yourself at home" and urged people to avoid at-home COVID-19 tests. In part, the FDA took action because the agency was trying to protect consumers from "fraudulent" test kits - scammers selling fake kits.

The following day, the FDA further clarified that the at-home COVID-19 testing, "including self-collection of samples to be sent to a clinical laboratory," were not included in the updated EUA policy exemptions issued on March 16.

Companies that had been ramping up at home COVID-19 tests are in regulatory limbo, and many have decided to tap the brakes on production.

Javitt said some of the companies that pulled back production were specifically distributing at-home collection kits. Consumers would collect a specimen at home, but the test itself would be done in a certified laboratory. The FDA took issue with a non-health care provider collecting the specimen.

"What was being distributed was just a collection device, and the FDA said it was not permitted to distribute those collection devices for specimens," said Javitt.

The San Francisco-based health startup Nurx launched its at-home COVID-19 testing kits on Friday but when "the FDA issued new guidance on Saturday specific to self-collection tests like the one we offer, exempting them from the EUA, we and our partner lab decided to make the responsible decision and pause our service for the time being."

Meanwhile, Texas-based Everywell, a company that has been offering more than 35 different kinds of at-home health test kits, built the infrastructure to start direct-to-consumer COVID-19 testing. Following the FDA's announcement, Everywell said it would switch gears and provide its kits to hospitals and health care companies until further notice.

"I do think many of the companies are being cautious because they are worried or cautious with the increased regulatory oversight going on with regards to them," said Dr. Amesh Adalja, Senior Scholar at Johns Hopkins Health Security Center.

Nurx and Everywell, among other health care startups now in limbo waiting for more clarity as to whether or not they can resume manufacturing and distributing their at-home tests.

"Certainly, there are competing considerations. We do not want fraudulent kits out there," said Javitt in regards to FDA's warning against at-home test kits. "At the same time, there are some legitimate reasons and obvious public health value to keeping people out of the public clinics, out of the hospitals and at home, whether they are negative or positive."

The FDA admits that safe and accurate home collection tests would expand availability of COVID-19 testing. The agency said it is working to "help in meeting the increasing demands for tests is "are actively working with test developers in this space." Such language suggests that COVID19 collection kits may in fact reach a person's front door in the near future.

Adalja agrees, admitting that the FDA's regulations are somewhat ambiguous.

"The home collection kits are not truly home test kits." For example, Everywell's at-home kit only provides a special swab that allows a user to collect a specimen from their nose at home. But you don't get the results right then and there. Instead, the specimen is sent to a lab for actual testing for COVID-19.

According to Everywell, "Our COVID-19 partner labs are CLIA-certified labs-many of which already offered infectious disease assays, including tests for other respiratory viruses. Many of these labs also already conduct diagnostic COVID-19 tests for hospitals and clinics in their regions."

Companies like Everywell have the existing diagnostic capacity, but the FDA is concerned with the integrity of at home specimen collection. The agency worries that patients won't be able to adequately collect samples with the potential to lead to false negatives.

In response to these concerns, a Texas-based company called MicrogenDX has validated a laboratory test that can detect the virus through coughed up saliva.

"Collecting a nasal swab, should be done by a health care provider because it really should go deep into the sinuses, but there is no health care provider involved in sputum collection," MicrogenDX CEO Rick Martin said in an interview with ABC News.

MicrogenDX is set to launch a new service where patients could directly request a COVID-19 kit online at home. While patients may have the option to send their saliva samples from the comfort of their own home, MicrogenDX says they are not a home collection kit. They say a physician must first authorize the test before a patient can order it online.

"It's up to the physician and the patient where they are going to collect that specimen," said Martin.

Javitt says this system -- a physician-prescribed at-home test, rather than one you order directly as a consumer -- falls into a regulatory "gray area."

"The FDA does not regulate the practice of medicine; they regulate product, and so once a physician has made a decision to send a kit there is some ambiguity where FDA authority would end," she said.

"At this point, I'm not allowing patients to order kits as a test kit. I'm allowing physicians to order them to be sent to patients," Martin said. If a patient wants a test they must receive a signature from their doctor. Once the doctor approves, the patient will receive an online code that will allow them to order the test online.

MicroGenDX's kit would cost $125 with a $10 shipping fee. Patient samples would be shipped overnight to their main lab in Lubbock, Texas, and receive their results through their doctor the following morning.

"We want maximal flexibility, within the bounds of what's feasible in the current FDA regulatory regime in order to get as many of these tests into people's hands as possible," said Adalja. Home test collection kits may be key in doing so, but as health and federal authors face an unprecedented public health emergency the regulations are working on catching up with the needs.

What to know about the novel coronavirus:

• How it started and how to protect yourself: coronavirus explained
• What to do if you have symptoms: coronavirus symptoms
• Tracking the spread in the US and worldwide: coronavirus map

The Bill and Melinda Gates Foundation is working with Amazon, for example, to offer home COVID-19 testing kits to people in the Seattle area, an area that has been particularly hard hit with COVID-19 cases. This initiative -- which is also supported by the University of Washington -- is meant to increase access to testing and help public health officials learn more about how the virus spreads.

Adalja notes that even outside the current COVID-19 pandemic, advocates and public health experts have been pushing for better access to at-home testing.

"The coronavirus pandemic, which has been marked by lack of diagnostic capacity, will underscore the need for these types of tests available in general," he said. "This will give us a pathway to increase diagnostic capacity very rapidly and also keeps people out of hospitals, doctors offices, emergency departments where they could potentially infect other people and create crowding."

Eden David, who's studying neuroscience at Columbia University and matriculating to medical school later this year, is a contributor to the ABC News Medical Unit. Sony Salzman is the unit's coordinating producer.