To test or not to test?

In a shift that perplexed some doctors, the US Centers for Disease Control and Prevention recently changed its Covid-19 testing guidelines to say some people without symptoms may not need to be tested, even if they've been in close contact with someone known to have the virus. Previously, the CDC said viral testing was appropriate for people with recent or suspected exposure, even if they were asymptomatic. Dr. Carlos del Rio, an infectious disease specialist and associate dean of Emory University School of Medicine, told CNN's Jim Sciutto on Wednesday that not testing may be OK in some circumstances -- brief contact, for example. "But if you have been in contact for 15 minutes and that [person] doesn't have a mask, I think you need to be tested regardless if you have symptoms or not," del Rio said. "We know especially young people going into the house and then transmit inside the household. So, the guidelines baffle me and I really don't understand them." This change in guidance came the same week the FDA announced an emergency use authorization for Abbott’s new 15-minute rapid antigen test. Antigen tests work differently and are less reliable than PCR tests. But there is hope that a test like this could be a game-changer, allowing many more people to access an affordable test that gives quick results.