Error Rates on Rapid Covid-19 Tests Put Nursing Homes on Edge

July 27, 2020

The new rapid Covid-19 antigen tests being sent to thousands of U.S. nursing homes in high-infection areas have a troubling flaw: They provide false negative results for about 15% of infected people.

As nursing home infections climb once again due to the resurgence of the coronavirus, a false negative test could prove dangerous and even fatal for facilities that don’t confirm the results and mistakenly provide access to an infected person, said Christopher Laxton, executive director of AMDA—The Society for Post-Acute and Long-Term Care Medicine.

“If you’re putting people into an environment where they may in fact have the virus, it just hasn’t been caught, you’re putting a lot of people at risk. And that certainly is true of staff, but it’s especially true for residents,” said Laxton, whose organization represents more than 50,000 medical directors, doctors and other providers who work in nursing homes and other long-term care settings.

The cheaper, faster tests—which diagnose Covid-19 infections in 15 minutes—are central to the Trump administration’s push to keep nursing homes safe. They’ll allow more facilities to screen and test residents and visitors, and provide weekly tests for employees—which the Centers for Medicare & Medicaid Services will soon require in upcoming guidance.

The stakes couldn’t be higher. As of July 24, nursing homes and other long-term care facilities in 42 states reported 59,506 Covid-19 deaths, according to the Kaiser Family Foundation. That’s 44% of all Covid-19 deaths in those states.

The Department of Health and Human Services said in an email to Bloomberg Law that negative antigen test results “from patients with symptom onset beyond five days, should be treated as presumptive” and shouldn’t be “used as the sole basis for treatment or patient management decisions, including infection control decisions.”

The HHS, the Food and Drug Administration, and the test manufacturers recommend confirming negative results with a more accurate polymerase chain reaction, or PCR, test if necessary.

The Trump administration already shipped 654 antigen testing devices to 635 nursing homes. It plans to send nearly 1,800 of the machines, which are made by Quidel Corp. and Becton, Dickinson & Co., within the next three weeks, said Adm. Brett Giroir, who heads the Trump administration’s Covid-19 testing efforts.

“By putting point-of-care (testing) in nursing homes we not only improve turnaround and protect our vulnerable there, but we offload a lot of the demand on the major laboratories” to process test results, Giroir said.

The new tests quickly identify certain proteins that are part of the coronavirus in samples collected by nasal swabs. The devices, the Sofia and Sofia 2 models made by Quidel and the Veritor Plus System by BD, can process between 20 or more tests per hour in steady succession using a technique known as “batch testing.”