New COVID Testing Guidelines for Home: How to Get an Accurate COVID Test Result

As the US enters the fall school season, rapid antigen tests to detect COVID-19 are back in the spotlight. But new guidance from public health agencies has left some Americans confused about how and when to best test for COVID at home.

Spurred by the availability of free tests from the government and health insurance covering the cost of kits, the use of at-home COVID tests increased dramatically at the start of this year, between the fall of delta and the rise of the omicron variant. Numbers from the Centers for Disease Control and Prevention show that more than 2.5 trillion home tests were produced for those in the US between October 2021 and May 2022.

Rapid COVID tests have become a popular diagnostic tool for avoiding viral transmission at private and public events, as well as at schools. However, new research suggests that at-home COVID tests may not return positive results for people who've recently been infected, prompting the US Food and Drug Administration to update its testing recommendations for those who've been exposed to COVID-19.

At the same time, the CDC has relaxed its guidelines around COVID-19 quarantines, virus exposure and screening testing. Learn how COVID tests work with the latest omicron variants, as well as why the FDA and CDC have updated their advice for home testing. For more on COVID, here's what to know about boosters this fall and which ones to get.

How do at-home COVID tests work?

At-home rapid antigen tests can detect the COVID virus without the need of laboratory equipment. In contrast with PCR tests -- which use amplification technology to find tiny genetic traces of COVID-19 -- at-home COVID tests react to molecules on the surface of the virus, collected on a nasal swab sample.

COVID rapid home tests are "lateral flow assays," much like over-the-counter pregnancy tests. A nasal sample is mixed with a chemical solution that extracts the antigen proteins. The solution then gradually soaks a test strip that changes color if its included COVID antibodies interact with any COVID proteins from the sample.

The tests are quick, taking about 15 minutes compared to one to three days for PCR test results. Yet while at-home COVID tests have highly accurate positive results, negative results are less conclusive. When the FDA announced the first emergency authorization of a COVID antigen test, it noted, "positive results from antigen tests are highly accurate, but there is a higher chance of false negatives, so negative results do not rule out infection."

What are some problems with at-home COVID tests?

At-home COVID tests have "lower sensitivity at low viral loads," according to Canada's National Collaborating Centre for Infectious Diseases. That means they're not great at detecting COVID at the early, asymptomatic or recovery stages of infection.

A large amount of the population -- 95% per a CDC study -- has developed some immunity to COVID-19 via vaccination or previous infection, and some scientists theorize that many COVID cases now may have less viral load compared to cases earlier in the pandemic. According to The Los Angeles Times, California health officials are warning that some COVID patients are testing negative with rapid antigen tests for several days after their first symptoms.

Other COVID researchers contend that the omicron variant of COVID may infect the throat more than the lungs, which could lead to less virus in the nasal passages. Some doctors have recommended swabbing the throat along with the nose when using at-home COVID tests, though others have pushed back on that advice.

What is the new FDA guidance for COVID testing at home?

For those with initial symptoms, the FDA now recommends taking two at-home COVID tests, 48 hours apart. For those exposed to COVID but not showing symptoms, the FDA recommends taking three at-home COVID tests, each also 48 hours apart.

The FDA based its guidance on new research from the National Institutes of Health and the University of Massachusetts School of Medicine. Their study showed that two rapid antigen tests two days apart detected COVID infections 94% of the time in people with symptoms. For people without symptoms, two at-home tests taken at the same interval detected COVID infections 63% of the time, but a third test increased that percentage to 79%.

What is the new CDC guidance for quarantining and testing for COVID?

The CDC "streamlined" its COVID guidance on Aug. 11, relaxing rules for quarantine, isolation for infected people and screening testing. 

The agency no longer suggests quarantine after a COVID-19 exposure. It instead recommends wearing a high-quality mask for 10 days and getting tested on day five.

The CDC also changed its policies on isolation for those infected with COVID-19. 

Infected people without symptoms or those who are fever-free for 24 hours with improving symptoms can end isolation after five days but should still mask for 10 days. People can stop masking earlier than 10 days if they received negative results from two rapid antigen tests taken 48 hours apart.

Also, the CDC's "How to Protect Yourself and Others" page no longer recommends keeping a six-foot distance from other people. Most important for schools and employers, the CDC now doesn't recommend the practice of "screening testing of asymptomatic people" as a preventive measure in community settings. 

Are new variants like omicron BA.4 and BA.5 detected by at-home COVID tests?

Yes, it seems that at-home COVID tests are as good at detecting the omicron variant of COVID-19 as they were detecting earlier variants like delta. An Aug. 8 research paper in Microbiology Spectrum reported that eight rapid COVID tests had "comparable sensitivities" to detect omicron BA.1 and delta.

Omicron variants BA.4 and BA.5 contain most of their mutations on the spike protein, which is not what triggers at-home COVID tests. At-home COVID tests are looking for the presence of COVID-19's nucleocapsid protein, which has had far fewer mutations.

Meriem Bekliz, lead author of the Aug. 8 paper, said that, "theoretically, there should be no difference in detection sensitivity between omicron BA.1 and its subvariants," in an interview with NPR.

How do I get at-home COVID tests?

COVID-19 tests are much easier to find now compared to a year ago, but they haven't gotten any cheaper. You'll still usually pay about $10 to $12 per test at retail stores. 

On Aug. 18, the cheapest tests we found online were the FlowFlex COVID-19 antigen test for $8 at Target, and a five-pack of iHealth COVID-19 antigen rapid tests for $45 ($9 per test) at Amazon.

Fortunately, there are a few ways to get at-home COVID tests for free. First, your household can claim up to 16 free tests from the federal government that are mailed through the US Postal Service.

If you've already received all your free government COVID tests, you can get at least eight tests per month per person if you are covered by health insurance. 

If you're not insured or have used up your limit of at-home COVID tests, you may want to try a community health center. Along with Medicare-certified rural health clinics, health centers have been provided COVID tests for distribution to patients at no cost.
You can search for a local health center at the Health Resources and Services Administration's website.

For more information about COVID-19, learn everything there is to know about the BA.5 subvariant and which countries have travel warnings due to high COVID levels.