You can test for COVID-19 at home with a rapid antigen test that gives results in about 15 minutes, or get a more sensitive PCR test through a clinic or lab. Rapid antigen tests are widely available at pharmacies and grocery stores without a prescription. Which test makes sense depends on your timing, symptoms, and what you plan to do with the result.
Rapid Antigen Tests vs. PCR Tests
The two main types of COVID-19 tests work differently. Rapid antigen tests detect proteins on the surface of the virus. PCR tests (also called molecular or NAAT tests) detect the virus’s genetic material and are significantly more sensitive. Lab-based molecular tests are generally more accurate than at-home antigen tests, which is why a single negative rapid test doesn’t always rule out infection.
The practical tradeoff is speed versus sensitivity. A rapid antigen test gives you an answer in minutes at your kitchen table. A PCR test requires a visit to a testing site or mailing a sample to a lab, but it can catch infections that a rapid test misses, particularly in the early days after exposure or when you don’t have symptoms.
When to Test After Exposure
If you were around someone with COVID-19 but feel fine, wait at least 5 full days after exposure before testing. Testing too early often produces a false negative because the virus hasn’t replicated enough to be detectable. If you develop symptoms before that 5-day mark, go ahead and test right away.
A single rapid test after exposure is not especially reliable. Antigen test sensitivity drops to just 18% on days when no symptoms are present, compared with PCR as the reference. That means a rapid test misses the majority of asymptomatic infections on any given day. If a PCR test isn’t available, serial testing (described below) is the best way to compensate for that gap.
How Many Tests You Actually Need
One negative rapid test is not enough to be confident you’re negative. The FDA recommends serial testing after any negative antigen result, whether or not you have symptoms.
- If you have symptoms: Test twice over 3 days (48 hours apart).
- If you don’t have symptoms: Test three times over 5 days (48 hours between each test).
Repeating the test matters because viral load rises over time. Modeling from the Infectious Diseases Society of America found that serial antigen testing in asymptomatic people with a known exposure pushed sensitivity from about 63% with a single test up to 86% with repeat testing. That’s a meaningful improvement when you’re trying to protect someone vulnerable or decide whether to attend a gathering.
How to Swab Correctly
Poor technique is one of the most common reasons for a false negative on a home test. Most at-home kits instruct you to swab the inside of both nostrils, but people often don’t go deep enough or rush through it.
Insert the swab about 1.5 centimeters (roughly half an inch to three-quarters of an inch) into your nostril, then rotate it gently against the inside wall for 10 to 15 seconds per nostril, or as long as your test instructions specify. You want to collect actual nasal secretions, not just touch dry skin. Leave the swab in contact with the nasal lining long enough to absorb moisture. Repeat in the other nostril with the same swab, then place it in the test solution promptly.
Some people also swab the back of the throat before swabbing the nose. The CDC notes that combining throat and nasal specimens can maximize test sensitivity. If your specific test’s instructions mention throat swabbing, swab the tonsil area on both sides while avoiding the tongue and teeth, then proceed with the nasal swab using the same swab.
Reading Your Results
A valid test shows a control line (usually marked “C”). If that line doesn’t appear, the test failed and you need to use a new one. A visible line at the test position (marked “T”) alongside the control line means the result is positive.
A faint line counts as positive. Even a barely visible pink or purple line at the “T” position is a positive result. Faint lines typically appear when viral load is lower, either early or late in an infection, but they still indicate the presence of viral proteins. There is no “kind of positive” with these tests.
A negative result, especially a single one, is less definitive. Antigen tests are better at confirming infection than ruling it out. Overall sensitivity sits around 47% compared with PCR, but it climbs to 77% on days when fever is present and reaches 56% when any symptoms are reported. If you feel sick and test negative, test again in 48 hours before assuming you’re in the clear.
When a PCR Test Is the Better Choice
A PCR test makes more sense when accuracy matters most. If you don’t have symptoms but had a known exposure, especially to someone at high risk, the Infectious Diseases Society of America recommends a PCR test over a single rapid test. PCR is also more useful early in infection, before viral load peaks, and for confirming a negative rapid test when you’re symptomatic.
PCR tests are available at clinics, urgent care centers, and some pharmacies. Results typically take anywhere from a few hours to a couple of days depending on lab capacity. One thing to know: PCR can remain positive for weeks after an infection because it detects residual genetic material, not just live virus. This makes it less useful for determining whether you’re still contagious after recovering.
Cost and Where to Get Tests
At-home rapid antigen tests typically cost $8 to $15 for a two-pack at pharmacies and retailers. Private insurance plans may offer reimbursement, though coverage varies by plan and has changed since the public health emergency ended in May 2023.
Medicare Part B still covers lab-conducted PCR tests at no cost, with no deductible or copay. However, Medicare stopped covering over-the-counter home tests after the public health emergency ended. Some Medicare Advantage plans still cover home tests as an added benefit, so it’s worth checking with your specific plan. For everyone else, PCR tests ordered by a healthcare provider are typically covered by insurance, though out-of-pocket costs depend on your plan.
What to Do After a Positive Result
Current CDC guidance, updated in March 2024, recommends staying home and away from others when you’re sick with COVID-19. You can return to normal activities once you’ve been fever-free for at least 24 hours without using fever-reducing medication and your symptoms are improving. This applies to COVID-19 and other respiratory viruses alike.
For the first few days after returning to activities, wearing a mask around others and improving ventilation in shared spaces reduces the chance of passing the virus along while your body finishes clearing it.