The new coronavirus variant—first detected in South Africa, and named Omicron by the World Health Organization—has stirred up concerns around the world. It’s sent stock markets on a roller-coaster ride, triggered new air travel bans, and raised a number of questions. President Joe Biden addressed the American public after Thanksgiving, calling for calm and stating the variant should be a “cause for concern, not a cause for panic.” “We have more tools today to fight the variant than we’ve ever had before,” he said at a White House press conference. “You have to get your vaccine—you have to get the shot, you have to get the booster.” Scientists are scrambling to understand how the mutations in Omicron may affect the virus’ transmissibility and mortality rate and whether or not existing COVID-19 vaccines are effective against it. Infectious disease expert Davidson Hamer is a member of Boston University’s Medical Advisory Group, which has …