Scott Pelley investigates if politics are preventing the scientific community from doing crucial research that could help find a vaccine for the coronavirus. The Internet giant continues take orders and send millions of packages each day, but some of its workers say Amazon isn't keeping its workforce safe. Lesley Stahl reports. They are virtually untraceable weapons that can be made at home using legally purchased parts. Ghost guns have turned up in criminal cases in most of the country. Bill Whitaker has the story. Those stories on this week's "60 Minutes."See Privacy Policy at https://art19.com/privacy and California Privacy Notice at https://art19.com/privacy#do-not-sell-my-info.