U.S. health officials are seeing an astonishing lack of demand for COVID-19 medicines that may help keep infected people out of the hospital, drugs they rushed out to states over the past few weeks as deaths set new records.

COVID-19 vaccines have begun shipping in the U.S. after getting emergency authorization, setting off the nation's biggest ever vaccination push. But supplies are expected to be limited for some time. A brief explainer on what to expect.

With President Joe Biden vowing to get elementary and middle school students back to the classroom by spring and the country’s testing system still unable to keep pace with the spread of COVID-19, some experts see an opportunity to refocus U.S. testing less on medical precision than on mass screening that they believe could save hundreds of thousands of lives.