The US Food and Drug Administration has granted an emergency use authorization for the first time to a COVID-19 diagnostic test that people can use at home.
Lucira Health, the company that makes the test, announced on Wednesday that the 30-minute diagnostic will be available by prescription only. The initial rollout will be at hospitals in California’s Sutter Health system and at the Miami-Ft. Lauderdale location of the Cleveland Clinic. Set to cost about $50, the test should be widely available by early spring 2021.
The test, called COVID-19 All-In-One, detects the genetic material of SARS-CoV-2, the virus that causes COVID-19. It does this through a technology called loop-mediated isothermal amplification (LAMP), in which the virus’ genetic material is converted to a form that can be copied by enzymes. If the test is positive, the pH changes and is read by a small hand-held device that the consumer receives. An LED light marked “positive” glows. Otherwise the test lights up as negative.
Lucira Health, formerly Diassess, is a small diagnostic company that earned funding from the US Biomedical Advanced Research and Development Authority to build an at-home flu test. The company switched its focus to COVID-19 when the pandemic started.
LAMP technology is well-suited to diagnostics, says Yu Lei, a biosensor expert and chemical engineer at the University of Connecticut. “I’m very glad that the LAMP technology is hitting the market,” he says.
LAMP is related to another molecular technique called polymerase chain reaction (PCR), in which genetic material is also copied. Traditional PCR is also what’s used in many molecular diagnostics for COVID-19, but it is slower, and requires a specialized machine to accommodate the different temperatures it cycles through. LAMP, in contrast, is done at a constant temperature, Lei says.
Another difference is the enzyme used in the assays. The traditional PCR enzyme builds copies of genetic material most efficiently and accurately at high temperature. The enzymes used in LAMP do not need that high temperature, and Lei says they often have an additional function that adds to speed: While one part of the enzyme helps build a copy of the virus’s genetic sequence, another part is ripping it up to serve as a template for the next copy.
But diagnostic experts have had concerns about LAMP’s accuracy. Lei, for example, says that sometimes the copying machinery makes copies of non-target genes, leading to false positives. Others have said that LAMP isn’t as sensitive as traditional PCR, meaning that there could be false negatives if a person’s viral load isn’t high enough to be detected.
This appears to be the case for the Lucira test. The company validated the test with people who were suspected of having COVID-19 by comparing it to another COVID-19 test that it didn’t identify but is presumably PCR. Where the reference test detected a positive COVID-19 sample, Lucira’s test agreed about 94% of the time. Low viral counts account for the discrepancy, the firm says. Negative test results agreed about 98% of the time.
The concept of at-home tests has also been criticized because it isn’t clear that people can successfully do their own nasal swabs. Lucira says that professionals watched volunteers as they did their own nasal swabs, and all of the roughly 100 people were able to do it.
While the authorization is exciting, there are still a lot of questions to be answered about at-home tests, says Scott Becker, CEO of the Association of Public Health Laboratories, members of which do COVID-19 testing. He says the infrastructure surrounding the test is important, from how it gets to people to how those results are reported to public health authorities. Without a clear system in place, at-home tests will not be useful as a strategy to prevent the spread of coronavirus.
“It’s not enough to put these on the market. There needs to be education around it, a system in place, and that’s an equally hard part to developing the test,” Becker says.