outbreak a global pandemic. our senior medical correspondent dr. sanjay gupta joins us to explain why. what makes it a pandemic? there are criteria that are somewhat defined to call something a pandemic. let me preface by saying this terminology that we re going to start using now isn t so much to cause panic but rather to really cause a focus on preparedness. sanjay will join us in a moment. more than 525,000 americans have died since sanjay made those remarks. but this morning there are so many positive signs. 2.2 million people a day are getting vaccinated. the cdc has new guidelines for 30 million people who are fully vaccinated. if you are one of them, the cdc says it is safe to gather with other vaccinated people indoors without masks. and vaccinated grandparents can safely visit unvaccinated grandchildren. but the experts say we re not out of the wood yet. coronavirus variants could still trigger another deadly surge, especially as states relax their guidelines.