When Should I Worry About...

How Reliable Are At-Home COVID-19 Test Kits Really?

Sep. 15, 2021 - Katie McCallum

We're a year and a half into this pandemic and somehow COVID-19 testing can still feel like a total mystery at times.

Where do I go to get tested? Which test do I need? How soon will I get my results?

In particular, many of us are looking for easier and faster ways to know if we're virus-free. And taking an at-home COVID test seems like a really convenient answer — especially considering that some deliver rapid results.

A quick test, a negative result (hopefully) and you're in the clear to go to that birthday party you don't want to skip, right?

Unfortunately, it's not that simple. Plus, since not all at-home COVID-19 test are rapid, how do you know which you need?

"The gold standard of COVID-19 testing is still a PCR test of a nasopharyngeal, or sometimes nasal, sample collected by a medical professional. At-home COVID tests can play a role during this pandemic. Just be sure to know the caveats of these tests and follow the instructions very closely," says Dr. Wesley Long, director of diagnostic microbiology at Houston Methodist.

Which at-home COVID test is best?

First, make sure whichever at-home COVID-19 tests you're considering are actually authorized by the FDA.

Next, it's time to consider the two types:

  • PCR test – you collect a sample at home and mail it out for laboratory testing
  • Rapid antigen test – you collect a sample at home, test it using the supplied kit materials and get your result in minutes

Which out of the two is right for you? It depends, and the answer may be both of them.

"Whether you have symptoms or not, a PCR test is always the most accurate and sensitive way of detecting the virus. Typically, it takes a few days to get your results from an at-home PCR test," says Dr. Long.

On the other hand, a rapid antigen test delivers quick results. But, Dr. Long cautions that antigen tests work best early in the course of the disease if you're having symptoms. If the test is negative, those results should still be confirmed by a PCR test. This detail is present in the package insert of most rapid antigen tests.

"If you've had a known exposure and are experiencing symptoms, a rapid antigen test might be a good way to quickly confirm that you're positive for COVID-19," says Dr. Long.

Rapid antigen tests aren't perfect. False positives — meaning your test is positive but you're not actually infected — are possible with antigen tests, although less likely if you're symptomatic.

"What's more concerning than a false positive, though, is a false negative. This is when your test is negative even though you're infected with COVID-19. False negatives are fairly common with antigen tests, so it's really important that a negative antigen test be confirmed with a PCR test — which is much more accurate and sensitive," explains Dr. Long.

One last thing to know is that PCR test results don't always have to take a few days.

"At Houston Methodist, we offer PCR tests with a prompt turnaround time. Sample collection is done at our locations, not at home, but we typically turn around the results in less than 24 hours," adds Dr. Long.

If you have symptoms or a confirmed COVID-19 exposure and are interested in a PCR test from Houston Methodist, get started by visiting with one of our Virtual Urgent Care providers.

Can at-home rapid COVID tests really make a gathering safer?

In a perfect pandemic world, you could try to plan a "safer" gathering by using at-home rapid antigen tests to make sure you and your guests aren't infected with COVID-19 beforehand.

Unfortunately, these tests aren't sensitive enough to make a gathering safe. And they may actually provide a false sense of security.

"Rapid antigen tests can easily miss asymptomatic infection. In fact, they're actually likely to be false negative in that time period and many are approved only for use in people with symptoms. I would advise against relying on at-home rapid antigen tests to 'screen' for COVID before a gathering, especially since a person can transmit the virus when he or she is asymptomatic," explains Dr. Long.

And if you're symptomatic before a gathering, an at-home rapid antigen test can confirm you're COVID positive — but did you really even need a test to determine that it's probably best to play it safe by taking a rain check and getting a PCR COVID-19 test instead?

At-home testing is not a substitute for vaccination, masking and social distancing

Whether you're trying to plan a safe gathering, deciding how to stay safe at work or just really want to risk it at that crowded indoor event, know that at-home COVID testing doesn't replace the preventive measures known to keep us safe during this pandemic.

The best ways to prevent the spread of COVID-19 are to:

  • Get vaccinated
  • Get tested if you're experiencing COVID-19 symptoms
  • Wear a mask
  • Social distance
  • Avoid indoor spaces with poor ventilation
  • Avoid crowds
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Categories: When Should I Worry About...