At-Home Flu Tests Are Surprisingly Accurate—So Why Don't We Have One Yet?

At-home tests for influenza are just as accurate as those used in doctors' offices, new research finds. Experts believe that the distribution of such tests—particularly following home testing done during the COVID-19 pandemic—could not only lead to earlier diagnoses, but potentially reduce infections on a national or global scale.

The news comes as part of the Seattle Flu Study, and was recently published in JMIR Public Health and Surveillance. Researchers ultimately determined that both the sensitivity and specificity of rapid diagnostic tests (RDTs) performed at home were on par with RDTs done in a clinical setting. Though public health experts had long suspected that at-home tests may not be as accurate as those performed or tested by health care professional, the new study shows that most people are quite good at testing themselves—and that the tests used are reliable.

"The main takeaway is that people at home, unsupervised, could do a simple self-test for flu with similar accuracy to if they'd been to the doctor," the study's senior author Matthew Thompson, DPhil, MPH, a professor of family medicine and global health at the University of Washington School of Medicine, told Health.com.

At-home flu tests approved by the FDA aren't currently available, likely because the demand for at-home testing didn't become fully apparent until COVID-19 hit. But the new research may be a step in the direction of changing that. Here's what you need to know about the accuracy of at-home flu tests, and when you may be able to expect them on store shelves.

Accuracy of At-Home Flu Tests

To figure out just how accurate rapid flu tests used at home are, researchers from University of Washington Medicine, Fred Hutchinson Cancer Research Center, and Seattle Children's Hospital recruited 605 participants in Seattle. The participants were mailed rapid influenza testing kits (made by Ellume), along with collection materials for a polymerase chain reaction (PCR) test that would be sent to a local laboratory.

The participants were instructed to swab their noses if they had a cough or other respiratory infection symptoms like sore throat, body aches, chills or fever. After completing the tests, they recorded their rapid tests results on an app and mailed the PCR samples back to a lab.

Between February to May 2020, 14% of the participants tested positive for influenza via PCR tests, a rate that was in line with the prevalence of influenza in the area during the time period. When compared to the PCR test results, which have been considered the gold standard of diagnostic testing throughout the COVID-19 pandemic, the at-home tests only caught about 60% of infections, which researchers labeled as "moderate sensitivity." When a rapid test identified an infection, they were often very good at identifying the strain of influenza (influenza A or influenza B).

But those results were expected, since RDTs in general are less sensitive than PCRs. When compared to previous data on RDTs performed in health care settings, the at-home tests were just as accurate at providing diagnoses. They each detected about 60% of infections, according to current data and pooled estimates from past studies. "Although it compares similarly to other antigen tests, it doesn't compare great to a PCR test," Daniel Rhoads, MD, FCAP, the vice chair of the College of American Pathologists Microbiology Committee, told Health.com.

The at-home tests were also found to be more accurate when performed in the first 72 hours following symptom onset. The chances of false-negative readings increased when the test was performed after that first 72-hour window, researchers said.

At-Home Flu Test Availability

A typical flu season sees up to 41 million infections, 710,000 hospitalizations, and 52,000 deaths. Home-based tests could dramatically improve the burden of influenza: People could be diagnosed faster through home tests, and the sooner infected people are diagnosed, the quicker they can begin isolating or taking treatments that shorten the duration and severity of their illness.

But there aren't currently any authorized at-home flu tests on store shelves—in fact, the only home-based, FDA-approved diagnostic test available in pharmacies, other than at-home COVID-19 tests, are is one used to identify HIV, approved by the FDA in 2012. "It is curious that none of the manufacturers had really been pushing self tests for other infections—flu or strep throat or other sexually transmitted infections," Thompson said. Many manufacturers probably didn't think there was a strong enough demand for home testing prior to the pandemic.

That doesn't necessarily mean scientists weren't working on any. Thompson said there were a handful of at-home flu tests in development before COVID-19 hit; some of which may have been already released if it weren't for the pandemic pushing back developments for other illnesses. Another hitch in scientists' plans: The lower-than-usual influenza numbers, due to COVID-19 mitigation strategies. "It's been very hard for test makers to actually finish their testing," Thompson said.

COVID-19 did, however, lay the groundwork for at-home tests, and show that people are interested in (and capable of) testing themselves at home. "Moving forward, with so much attention over the last two years put toward respiratory viruses, there's probably increased interested, or market demand, for at-home respiratory virus testing," said Dr. Rhoads.

Multiple at-home flu tests are now back in development: Lucira Health, a company focused on at-home diagnostics, has reportedly developed a dual COVID-19 and influenza test anticipated for the 2022–2023 flu season. Meanwhile, health care technology company Cue Health is also actively testing their own at-home influenza test, and Ellume—the makers of the test used in the Seattle study—already has an at-home flu test that they plan to share updates on soon.

We could start to see rapid flu tests on the shelves at pharmacies next winter, said Thompson. And hopefully, just like with COVID-19, these at-home flu tests could help expand access to testing, lower medical care costs, and kickstart treatments or encourage people to lay low to stop further spread.