How often you should test for COVID depends on whether you have symptoms. If you do have symptoms, the current recommendation is two rapid antigen tests spaced 48 hours apart. If you don’t have symptoms but suspect exposure, you need three tests over five days, each 48 hours apart. A single negative rapid test isn’t reliable enough to rule out infection on its own.
Testing When You Have Symptoms
If you develop a sore throat, cough, fever, or other symptoms that could be COVID, take a rapid antigen test right away. But don’t stop there. A single rapid test catches only about 59 to 65 percent of infections at their peak, which is around day three after symptoms start. If your first test is negative, take a second one 48 hours later. Two negative results spaced two days apart give you much more confidence the result is accurate.
Timing matters more than most people realize. Rapid tests detect the virus best when your body is shedding the most viral particles, and that peak doesn’t always line up with the first day you feel sick. For people who develop a fever, sensitivity is highest around two days after symptom onset, reaching about 80 percent. For those with milder symptoms like congestion or fatigue, the sweet spot is closer to day three. If you test on day one and get a negative, that’s not unusual, and it doesn’t mean you’re in the clear.
Testing After a Known Exposure
If you were around someone who tested positive but you feel fine, wait at least five full days after the exposure before testing. Testing too early often produces a false negative because the virus hasn’t replicated enough to be detectable yet. After that five-day window, take a rapid test and then repeat it twice more, spacing each test 48 hours apart. You need three negative results over five days to confidently rule out infection when you have no symptoms.
This three-test protocol exists because asymptomatic infections produce lower and more variable amounts of virus. A single test might catch you on a day when viral levels are just below the detection threshold. Serial testing closes that gap.
Testing to End Isolation
If you’ve tested positive and want to know when you’re no longer contagious, the guideline is straightforward: you need two consecutive negative tests taken at least 24 hours apart. This applies whether you use a rapid antigen test or a lab-based test. Once you hit two negatives in a row, you can feel more confident about being around others.
Keep in mind that some people continue testing positive on rapid tests for a week or longer, especially if they had a more severe infection. If you’re still getting positives after several days, keep testing once a day until you get that first negative, then confirm with a second negative the following day.
If You Had COVID in the Last 90 Days
Recent infection complicates things. If you tested positive within the last 30 days and don’t have new symptoms, testing again isn’t recommended because residual virus can trigger a positive result that doesn’t reflect a new, active infection. If you do develop new symptoms within that 30-day window, use a rapid antigen test rather than a PCR test. PCR tests are more sensitive and can stay positive for weeks after an infection has resolved, making them less useful for distinguishing old from new.
Between 31 and 90 days after a previous positive, you can test with a rapid antigen test whether or not you have symptoms. Follow the same serial testing rules: two tests 48 hours apart if symptomatic, three tests over five days if not.
Testing After Antiviral Treatment
If you took an antiviral like Paxlovid and your symptoms improved but then came back, that’s sometimes called rebound. You don’t need to routinely test after finishing treatment if you’re feeling better. But if symptoms worsen again after that initial improvement, take another rapid test to check whether the virus has become detectable again. Some people experience rebound symptoms two to eight days after finishing their course, and a positive test at that point suggests you may still be contagious.
Rapid Tests vs. PCR Tests
Rapid antigen tests are the standard for home testing and serial testing protocols. They’re less sensitive than PCR tests on any single use, picking up roughly 59 percent of infections at peak compared to 83 percent for PCR. But their advantage is speed, accessibility, and the ability to repeat them easily. When used in a series (two or three tests over several days), rapid tests become much more reliable.
PCR tests are better suited for situations where you need a single, highly accurate result, like before a medical procedure or if you’re at very high risk for complications. They’re typically processed at a lab and results can take a day or two. The main drawback is that they can detect viral fragments long after you’ve recovered, which is why they’re not recommended for people who tested positive in the previous 30 days.
Practical Tips for Accurate Results
Check the expiration date on your test kit. The FDA has extended shelf life for many brands, so check the manufacturer’s website if your box shows an older date. Store tests at room temperature, not in a hot car or freezing garage, since temperature extremes can degrade the testing strips.
Swab technique also affects accuracy. Most current rapid tests use a nasal swab, and you need to rotate it inside each nostril for the full time specified in the instructions, usually 15 seconds per side. Rushing this step reduces the amount of virus you collect and makes a false negative more likely. If you’re symptomatic and your nose is dry, some tests now allow throat swabbing, but only follow the method listed in your specific kit’s instructions.