COVID-19 Test: Which One, When to Test, and How to Read Results

Need a COVID-19 test but unsure which one fits your situation? You’re not alone. I’ll walk you through the main test types, when each works best, and what to do after a positive or negative result. No fluff—just the facts you can use today.

Which COVID-19 test should I pick?

There are two common tests: PCR and rapid antigen. PCR tests are done in labs and find tiny amounts of viral genetic material. They’re the most sensitive and are a good pick if you need a reliable result for travel or medical reasons. Rapid antigen tests look for viral proteins and give results in 15–30 minutes. They’re cheaper, faster, and work best when you have symptoms and likely a higher viral load.

At-home kits are mostly antigen tests. They’re handy for quick checks before visiting someone or after possible exposure. Some services sell at-home PCR kits that you mail to a lab—those combine convenience with higher accuracy, but turn-around time is longer.

When to test and how timing affects accuracy

Timing matters more than most people think. If you were exposed but feel fine, testing immediately often misses infections. For antigen tests, wait about 3–5 days after exposure or test as soon as symptoms appear. If your first antigen test is negative but you still suspect infection, repeat in 48 hours. PCR tests can detect infection earlier and stay positive longer—useful if you need a definitive answer within a few days of exposure.

Symptoms change the game. If you have a fever, cough, or loss of taste/smell, take a test right away. If your test is negative but symptoms are strong, follow up with a PCR or repeat the antigen test after a day or two.

Use the right sample: most home and clinic tests use nasal swabs; some PCR tests accept saliva. Follow the kit instructions exactly—shallow vs deep swab matters for accuracy, and improper handling can give false results.

How to interpret results and what to do next

If you test positive: isolate immediately, tell close contacts, and follow local health guidance. Most people can end isolation after 5 days if symptoms improve and you’ve been fever-free for 24 hours; keep wearing a mask around others for days 6–10. Seek medical help if you have trouble breathing, persistent chest pain, or severe weakness.

If you test negative but were exposed or feel sick: do another test in 48 hours or get a PCR. A single negative antigen test early after exposure isn’t a guarantee. For travel or medical procedures, confirm which test type is required—many places still ask for a lab PCR.

Buying and using tests smartly: choose FDA-authorized or locally approved kits, check expiration dates, and store them as instructed. When using at-home tests, follow steps exactly and read results in the time window the manufacturer specifies. If an online source seems suspicious or prices are way too low, pick a different vendor.

Questions about a specific test result or which kit to buy? I can point you to reliable options and explain sample steps for a few popular at-home kits.