Mark Warschauer, a professor of education at the University of California, Irvine, was “tremendously excited” about the authorization of Covid-19 vaccines, and happy when he became eligible to get his first doses. And he was at the front of the line to get a booster, too. “We were very concerned about Covid,” he told CNN. “I’m not elderly, but at the age of 67 I knew there was a substantial risk of hospitalization and even death from Covid. So I got my vaccine at the earliest possible date.” Warschauer is leading a trend.