New At-Home Covid Test Gets Green Light From F.D.A.

Unlike similar at-home tests, Ellume’s does not require a prescription.

The Food and Drug Administration on Tuesday issued an emergency authorization for the country’s first coronavirus test that can run from start to finish at home without the need for a prescription.

People as young as 2 years old are cleared to use the test, which takes just 15 to 20 minutes to deliver a result. Unlike many similar products, which are only supposed to be used by people with symptoms of Covid-19, this test is authorized for people with or without symptoms.

The test, developed by the Australian company Ellume, detects bits of coronavirus proteins called antigens. It’s slightly less accurate than gold standard laboratory tests designed to look for coronavirus genetic material with a technique called polymerase chain reaction, or P.C.R. But in a clinical study of nearly 200 people, Ellume’s product was able to detect 95 percent of the coronavirus infections found by P.C.R., regardless of whether the infected people felt sick. It also correctly identified 97 percent of the people who received negative laboratory test results.

Ellume, which was awarded a $30 million grant from the National Institutes of Health, said it planned to manufacture and deliver about 20 million home coronavirus tests to the United States within the first half of 2021. Each kit, which tests a single swab sample, is expected to cost about $30 or less, said Bella Zabinofsky, a spokeswoman for the company.

In a statement, the F.D.A. commissioner Dr. Stephen M. Hahn called Ellume’s authorization “a major milestone in diagnostic testing for Covid-19” in light of the coronavirus’s persistent grip on the nation. The product will be available in drugstores, Dr. Hahn noted, and gives Americans “more testing options from the comfort and safety of their own homes.”

Ellume’s test works best in people with Covid symptoms. In people without symptoms, the product’s accuracy dropped a bit, finding 91 percent of the coronavirus infections discovered by P.C.R.

Dr. Valerie Fitzhugh, a pathologist at Rutgers University, noted that all of the study’s false positives occurred in the asymptomatic group. That “does make me a little nervous,” Dr. Fitzhugh said. False positives could send people into unnecessary periods of isolation or erode trust in testing, among other issues.

In a statement announcing Ellume’s emergency clearance, the F.D.A. underscored the importance of recognizing false positive and false negative results, both of which are more common with antigen tests. People without symptoms who test positive, the agency said, should confirm their results with another test, especially if the coronavirus is scarce in their community. When very few people in a region are infected, the number of false positives yielded by tests can outnumber true positives.

Still, in broad strokes, “the performance looks better than what we’ve seen for other antigen tests,” said Susan Butler-Wu, a clinical microbiologist at the University of Southern California’s Keck School of Medicine.

The test’s price tag — compared with some competitors that cost just $5, for example — and limited availability will likely restrict it from very frequent use, Dr. Butler-Wu said. But in single-use contexts, “what’s really exciting is, it allows me to get a really quick answer if I’m feeling unwell. To me, that’s the most powerful thing.”

Laboratory tests, which have unparalleled accuracy in detecting all types of diseases in clinical settings, remain a crucial part of the coronavirus testing pipeline, Dr. Butler-Wu said. But skyrocketing caseloads across the country have continued to strain laboratory supply chains and personnel processing P.C.R. tests, which may take several days to return results.

A test that can deliver immediate results could allow someone to promptly begin their isolation and break the chain of transmission. People carrying the coronavirus are thought to be most contagious in the few days before and after their symptoms start, if they experience symptoms at all.

Ellume’s test starts with a self-collected nasal swab. (Children younger than 16 must be swabbed by an adult.) Plugged into a cartridge, the sample is analyzed, then pings data to a smartphone via Bluetooth. The results go to the person taking the test, and can be shared with health care providers and public health authorities.

The built-in reporting system is crucial, Dr. Butler-Wu said. Experts have previously raised concerns about at-home testing, in part because it could distance a person’s coronavirus test result from experts keeping tabs on where and how quickly the virus has spread.

Last month, the F.D.A. granted an emergency clearance to another at-home coronavirus test made by Lucira Health. Lucira’s test is pricier, estimated at up to $50, and can’t be used outside of a health care setting by children younger than 14. The test also requires a prescription and had not been evaluated in people without symptoms when the company submitted data to the government.

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