Last winter's flu season was the deadliest since the 1970s—79,000 people died—and a report released by the CDC Thursday might explain why. Per the report, just 37.1% of adults were vaccinated last season—the lowest rate since the 2010-11 season, and a drop of 6.2% from the season prior. "That’s huge. It’s a striking inflection down from the previous year," one infectious disease expert tells the Washington Post. Experts say the low level of vaccinations likely contributed to the particularly deadly year, though there were other factors as well, including a particularly harsh strain of the virus: H3N2 was dominant, and that strain typically results in the most complications and is also harder for the vaccine to fight. Experts are hoping more people will get vaccinated this year, with a CDC chief pointing out now "is the perfect time" to do so before flu season kicks into high gear. (For the first time in two decades, a new flu drug.)