It’s been a few weeks since the federal government began mailing out the free Covid-19 testing kits promised by the Biden administration, and it’s finally become easier to find rapid tests in stores. But even with Omicron’s surge on the decline, the pandemic isn’t over. Concerns remain about Omicron’s sister, and a new variant can always arrive. So what’s the most efficient way to use the government’s free tests? Whether you’re vaccinated, boosted, unvaccinated, or recovered, when should you test for Covid-19 and how should you interpret the findings?
Like so much of the advice and data during the pandemic, it’s complicated. When you should test and what the results mean—or don’t mean—depend on your individual circumstances. ”You can’t just have one rule that applies to everyone because there is variation around test results,” says Esther Babady, chief of the clinical microbiology service at Memorial Sloan Kettering Cancer Center in New York. “We like to make recommendations with data, and the thing that has been so frustrating with the pandemic is that you just don’t have enough time to gather the amount of data that we are used to getting before we can say anything.”
And what we say today might be different several weeks from now, points out Susan Butler-Wu, director of clinical microbiology and an associate professor of clinical pathology at the University of Southern California Keck School of Medicine in Los Angeles.
“The calculus changes at various points in the pandemic,” Butler-Wu says. When Omicron rates were raging, going to a bar or restaurant could practically guarantee that you’d be there with someone who had Covid-19 and didn’t know it. But, she adds, most people aren’t staying home full-time anymore and aren’t likely to wear a mask around their family because they went to a bar. We have to consider what’s practical too, she says.
We’ll start with the handful of clear-cut situations when you should definitely test. Most of this advice focuses on rapid antigen tests, but we’ll also note when to consider PCR testing and why.
Test if You Have Symptoms
If you have Covid-19 symptoms, test yourself no matter what your vaccination status or Covid-19 history is. You don’t need to test for every headache you have, but fever, cough, or a stuffy or runny nose should definitely trigger a test. It might be annoying during the winter when flu, colds, and other viruses are also circulating, not to mention the allergies that will descend on many people as spring draws closer. But if you blow off that sore throat or sniffle or cough and don’t test, especially if you’re not wearing a mask around others, you risk infecting someone’s grandmother or child or father or … you get the idea. Even if vaccination rates are high in your area, plenty of vaccinated, boosted people are immune-compromised or otherwise high risk. Exposing them could kill them. So, if you have symptoms, be a good human and test.
Test if You’ll Be Traveling
If you’re flying internationally, check the destination country’s requirements—you’ll probably need to show a negative test result, even if you’re vaccinated. If you fly into the US, you’re required to show a negative test result or proof of a recent Covid-19 recovery, regardless of your vaccination or citizen status. Even if you’re traveling within the US, the CDC recommends that anyone not fully up to date with Covid-19 vaccination (including boosters) get tested before leaving.
Test if You’ll Be Around Someone Particularly Vulnerable
Many people have returned to normal or mostly normal lives—visiting restaurants and bars and coffee shops, going to the movies, gathering with friends, etc.—but millions of immune-compromised individuals still have to be extra careful. Some don’t build up enough antibodies in response to the vaccine. Others might have antibodies but an immune system too weak to effectively fight off a breakthrough infection.
If you’ve been living a normal-ish life, especially without wearing a mask or taking other precautions, you should test before visiting anyone at particularly high risk, even if you don’t have symptoms. High-risk folks include organ transplant recipients, people undergoing active cancer treatment or living with a blood cancer, people with immune-compromising conditions or taking immune-suppressing medication, people particularly frail and elderly, and anyone with multiple serious underlying conditions that, even if vaccinated, makes them high risk with a breakthrough infection. Test twice 24 hours apart if you use a rapid test, but if you have any symptoms or think you might have been exposed and you can’t delay your visit, consider a PCR test, Babady says.
“If the person I’m going to see does not have a regular immune system, or even if they were vaccinated, I’m going to want to use the most sensitive test possible to make sure I’m not exposing that person,” Babady says.
Test When You Feel Recovered From Covid-19
If you had Covid-19 but your symptoms have subsided, test to confirm you really are Covid-19-free. PCR tests can remain positive days or sometimes weeks after you’re no longer infectious, but a negative rapid antigen test means it’s less likely you’re still infectious. Your school or work might also require a negative test to return.
Also keep in mind that, regardless of CDC recommendations, there’s a good chance you’re still infectious more than five days after initially testing positive, another reason to test before rejoining the world. One study, for example, found that half of people infected with Omicron still had high viral loads at day 5, suggesting they were likely still contagious.
What if I’ve Been Exposed?
If you know you’ve been exposed, test five days after the exposure. What you do during those five days depends on your vaccination and infection history.
If you’re unvaccinated, or vaccinated but not boosted, and you haven’t had Covid-19 in the past three months, you should quarantine at home during those five days and wear a high-quality mask around household members—an N95, KN95, KF94, or similar respirator mask that fits well. If you must leave the house, wear the best mask you can find and make sure it fits. And stay away from others.