Will At-Home Covid Tests Make Any Difference?

The problem is that the test relies on the honor system whereby those taking the test at home are expected - but not required - to report test results to their doctor. If they do not, out of fear of having to quarantine and losing pay or job, then there is little evident benefit. 

And even if there is widespread reporting of results, if not accompanied by mask-wearing and social distancing, as well as a drop off in risky behavior like gathering at indoor bars and restaurants, there is likely to be little improvement in infection rates. JL

Katherine Wu reports in the New York Times:

The FDA (approved) the first rapid coronavirus test that can run from start to finish at home, paving a path for more widespread testing. With a simple nasal swab, the test can return results in half an hour, and is projected to cost $50. People taking the test report the results to their health care providers, who must then inform public health authorities. Experts have raised concerns about the practicality of a strategy that would likely rely on tests that sacrifice accuracy for convenience and a more affordable price.

The Food and Drug Administration on Tuesday gave an emergency green light to the first rapid coronavirus test that can run from start to finish at home, paving a potential path for more widespread testing outside of health care settings.

The test, developed by the California-based company Lucira Health, requires a prescription from a health care provider. People under the age of 14 also cannot perform the test on themselves. But with a relatively simple nasal swab, the test can return results in about half an hour, and is projected by the company to cost $50 or less, according to the product’s website. Clinicians can also run the test on patients, including children under the age of 14, potentially delivering answers during a single visit to a care center or pharmacy, instead of routing a tough-to-collect sample through a lab.

A handful of other tests have been cleared by the F.D.A. for at-home collection of samples, which are then shipped to a lab for processing. But Lucira’s test is the first to remove the need for an intermediary.

“Today’s authorization for a complete at-home test is a significant step toward F.D.A.’s nationwide response to Covid-19,” Jeff Shuren, director of F.D.A.’s Center for Devices and Radiological Health, said in a statement. “Now, more Americans who may have Covid-19 will be able to take immediate action, based on their results, to protect themselves and those around them.”

People who test positive for the coronavirus are expected to isolate themselves from others for 10 days from the day their symptoms started, or the day they tested positive, per guidelines from the Centers for Disease Control and Prevention.

Laboratory tests that look for the coronavirus’s genetic material using a technique called polymerase chain reaction, or P.C.R., are still considered the gold standard for detecting the virus. But the new at-home test relies on similar principles by using a method called a loop mediated amplification reaction, or LAMP. Like P.C.R., LAMP repeatedly copies genetic material until it reaches detectable levels, making it possible to identify the virus even when it is present at only very low levels in the respiratory tract. While faster and less cumbersome than P.C.R., LAMP is generally thought to be less accurate.

People taking the battery-powered test must swirl a swab in both of their nostrils, then dip and stir the swab into a vial of chemicals. That vial is then plugged into a test cartridge that processes the sample. Within half an hour, the test cartridge will light up as “positive” or “negative.” Federal guidelines note that people taking the test should report the results to their health care providers, who must then inform public health authorities to help track the virus’s spread.

An at-home test for the virus “was going to happen,” said Omai Garner, a clinical microbiologist and diagnostics expert at the University of California, Los Angeles Health System. “I am hopeful that it works well.”

Dr. Garner said the news should be taken with a note of caution, however. In recent months, several experts have called for more widespread at-home testing as a way to help curb the virus’s spread. But others have raised concerns about the practicality of a strategy that would likely rely on tests that sacrifice a degree of accuracy for convenience and a more affordable price tag.

According to the product’s instructions, Lucira’s LAMP test was able to accurately detect 94 percent of the infections found by a well-established P.C.R.-based test. It also correctly identified 98 percent of the healthy, uninfected people.

Representatives at Lucira Health did not respond immediately to requests for comment.

Saskia Popescu, an infection prevention expert and epidemiologist at George Mason University, also cautioned that home testing, while a notable advance, should not be seen as a panacea. To help fill more of the gaps in coronavirus diagnostics, Dr. Popescu said, “We need more accessible and fast lab-based testing.”