Communities around the globe are facing new COVID-19 surges and outbreaks. Brazil experienced a record daily tally of infections this week: 115,000 in 24 hours. Cases are picking up in parts of Africa, where oxygen and vaccines are in short supply. But even Israel, which has led the world in its speedy vaccination campaign, has reimposed a mask mandate amid new outbreaks. William Hanage, an epidemiologist at Harvard’s T.H. Chan School of Public Health, views that move as an important, proactive measure as the virus evolves. He speaks with host Carol Hills about how variants and vaccines are changing the course of the pandemic right now.