CHANGWON, South Korea — If you visit your doctor with symptoms of joint pain, swelling, and stiffness, the diagnosis could be many different things. Is it osteoarthritis or rheumatoid arthritis?

Two types of COVID-19 tests, the rapid antigen test and the polymerase chain reaction (PCR) test, are available in the United States. The PCR typically relies on lab testing and is still considered ...

NEW YORK -- Millions of Americans have purchased rapid COVID-19 tests online or at local stores and signed up to receive test kits through a free government program. Unlike conventional, lab-processed ...

Rapid tests detect parts of the virus that are present in the sample collected from your nose or mouth. If the virus has not replicated to a high enough level in that part of your body, a test will be ...