Want a handful of free at-home Covid tests? The Biden administration has a new website, covidtests.gov, where you can order them.
The website, which officially launched>How accurate are at-home rapid antigen tests?
At-home tests detect small viral proteins called antigens, which require users to rub a nasal swab inside their nostrils a few times each side and then expose the swab to a few drops of chemicals. Results typically take about 15 minutes.
According to the Centers for Disease Control and Prevention, at-home antigen tests like BinaxNow are roughly 85% accurate at detecting positive cases. That means at-home tests miss roughly 15% of positive cases, which can sound like a high figure, especially when millions of people get tested each day.
But rapid tests aren't far behind the accuracy levels of polymerase chain reaction (PCR) tests, which are "considered to be the gold standard" in Covid testing, says Gigi Kwik Gronvall, a senior scholar at the Johns Hopkins Center for Health Security.
PCR tests detect genetic material or fragments from specific organisms or viruses, such as Covid-19. They can tell if you're currently infected, or if virus fragments are hanging around in your system after you're no longer infected. The downside is that they take time: Results can>When should you take an at-home test instead of a PCR test?
The short answer: If you think you're experiencing Covid symptoms, take a rapid antigen test. If you're asymptomatic, but concerned about potential exposure to the virus, take a PCR test.
"Rapid antigen tests are excellent tools to tell people if they are currently infectious and should isolate," Gronvall says.
If you have Covid, you'll be "the most contagious" when you're first experiencing symptoms, Gronvall says. That makes rapid tests much more likely to confirm or deny your infection: The more of a "viral load" you have, the more likely a rapid test is to catch it.
Crawford agrees: "[T]hat is when the 'viral load' is highest, and is what the tests were originally approved for by the FDA
Gronvall's advice for first-time users of at-home tests: Watch a how-to video before getting started. "[T]he second time someone does it is super easy, but it's not something people usually do," she says. "So for the first time, it might be helpful to watch a video."
Rapid antigen tests aren't as sensitive for people who are asymptomatic, Crawford says. That makes PCR tests more useful if you've been exposed to Covid but still feel fine, or if you simply want to be screened for ease of mind.
"There is a higher chance of an at-home test being negative in an infected asymptomatic person, when compared with a laboratory-based PCR test," Crawford says.
In addition to the Biden administration's free at-home Covid tests, multiple at-home rapid tests are available for purchase without a prescription, including Abbott's BinaxNow tests, the Ellume Covid-19 Home Test and the Quidel QuickVue At-Home Covid-19 Test.
Prices range from about $14 to $35, according to online websites.
