At-Home Covid-19 Tests Are Here, But Can You Trust Them?

Testing for Covid-19 has become somewhat easier for people in the United States. While there was a severe shortage of tests in the early weeks and months of the pandemic, more recently, many states have made testing sites available for people who have exhibited symptoms of the disease and even those who are asymptomatic.

According to the Centers for Disease Control and Prevention (CDC), as of June 4, more than 19.8 million tests have been performed in the U.S. (About 11% were positive.) Depending on how states report testing, these figures include two types of tests—those that check to see if you currently have an infection with SARS-CoV-2, the virus that causes Covid-19, and antibody tests, which can determine if you have been infected with the virus in the past.

The tests used to diagnose a current infection rely on a nasopharyngeal (back of the throat and nose) swab and look for the genetic material of the virus. These types of tests, known as viral tests, can pick up the virus while it’s actively in your body. Once the virus is gone, it can take 1 to 3 weeks for the body to generate antibodies. A blood test can then look for the antibodies to see if you were infected with the virus at some point in the past.

Both types of tests are available through testing facilities, hospitals, and doctor’s offices. However, some commercial medical manufacturers such as Everlywell and Pixel by LabCorp are also selling at-home collection kits that use the nasopharyngeal swab to detect an active infection. The U.S. Food and Drug Administration (FDA) has also approved an at-home collection kit that uses saliva, which was developed by Rutgers Clinical  Genomics Laboratory.  (There are no approved, at-home tests for antibodies yet.)

In general, tests have been authorized by the FDA under an emergency use authorization (EUA), meaning they aren’t officially approved in the traditional sense but have been authorized for use because of the public health crisis. The newest rapid Covid-19 antigen test approved by the FDA provides results in 15 minutes and will cost just $5

But not all Covid-19 at-home tests are the same. Early in the pandemic on March 20, the FDA issued a consumer alert about Covid-19 tests, warning that some may be “fraudulent” and “unauthorized.”

Although now that there are some authorized home tests available to consumers, how reliable will they be and can they help fight the current pandemic?

There are different kinds of at-home tests

In general, home tests allow you to test for—or monitor—diseases or conditions at home. They offer convenience and privacy and can be cost effective, says the FDA.

These tests fall into one of two categories, says Jacqueline Linnes, PhD, Marta E. Gross assistant professor of biomedical engineering at Purdue University in West Lafayette, Indiana. The first type includes at-home collection tests that involve taking a sample at home (for example, a nasal swab or saliva sample) then sending it to a lab for actual testing and results. The second type of at-home test allows you to both take the sample and get the result at home.

There are dozens of both types on the market, from home pregnancy kits to tests for HIV and other sexually transmitted diseases, hepatitis, urinary tract infections, blood glucose levels and even ketosis tests for people following the keto diet, says Dr. Linnes, whose lab is working on a handheld portable device that could test for Covid-19 and other viruses.

Many types of at-home tests are accurate

The reliability of a test really depends on which test you’re talking about. Home tests that have been approved by the FDA and have been around a while are generally quite reliable. (Look for their accuracy rating on the packaging or the manufacturer’s website.) One home HIV test, says Dr. Linnes, is 99.9 percent accurate.

“One of the keys to a reliable home test will be adequate sample collection,” says S. Wesley Long, MD, assistant professor of pathology and genomic medicine at Houston Methodist Hospital. “Home testing or monitoring for conditions like hypertension or diabetes is well established and useful, and typically uses FDA-approved medical devices.” Dr. Long points out, however, that this type of test is for monitoring people who have already been diagnosed with a condition. The tests are not used to actually diagnose the condition. Home testing for diagnosis is relatively new.

Another issue is the quality of the instructions. “I think that people can do these things if you give them really good instructions,” says Dr. Linnes.

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At-home Covid-19 tests have pluses and minuses

Both the Everlywell and Pixel tests are at-home collection tests. This means you get a kit that contains everything you need to get a nasopharyngeal swab. You are responsible for doing the actual swab and sending it off to the lab. The lab will do the testing and get the results, often within 48 hours.

The collection method is a concern for some experts. On the podcast, Sawbones: A Marital Tour of Misguided Medicine, Sydnee McElroy, MD, said the main problem was the consumer’s ability—or inability—to collect an adequate sample on their own. “It’s not something you as a lay consumer at home would necessarily be skilled at doing,” she said in the podcast. “It’s difficult for me to swab myself and I know how to do this. I’ve been trained.” That would throw into doubt the validity of any results. “If you don’t get a decent sample because it is so uncomfortable then you’re going to get a false negative result and then you might think you don’t have it when you do, which is bad.”