Republican lawmakers were responsible for 86 percent of anti-vaccine bills introduced across state legislatures in the years following the onset of the pandemic, according to Boston University School of Public Health (BUSPH). In Boston, the researchers categorized 1,513 vaccine-related bills introduced in state legislatures between 2019 and 2023, drawing on the State Vaccine Policy Project (SVPP). In 2019, state legislatures introduced 386 vaccine-related bills; by 2021, that number had ballooned to 1,154. Indeed, 24 percent of anti-vaccine bills introduced during the period gathered enough support to become law. "Our work shows that state lawmakers affiliated with the Republican party are responsible for the overwhelming majority of anti-vaccine bills introduced in recent years," study corresponding author Dr. Matt Motta said in a statement.