Every American traveling abroad needs to take an antigen test to return to the United States. But the start of the trip is often even more cumbersome, as many other countries (nearly every one I have ...

Polymerase chain reaction (PCR) is a fundamental molecular biology tool that scientists use to amplify and analyze genetic material, such as DNA and RNA. PCR involves the enzymatic amplification of ...

(CNN) -- One is widespread but has key shortages across its supply chain. One remains questionably reliable and is only helpful after the fact. And one is still early in development -- but could speed ...