Officials see the expanded eligibility as a way for the state’s 6 million residents to move “closer to herd immunity,” but they have stopped short of adding it to the required immunizations for schools, Mr. Gischler said. “There is currently no mandate to get vaccinated, but we encourage everyone who is eligible to do so to protect themselves, their families and their community,” Mr. Gischler said in the email. “At this time, there are no known plans to add COVID-19 vaccine to the list of immunizations required for school.” In Montgomery County, the state’s most populous jurisdiction, officials are using local vaccination rates to determine when and how to ease coronavirus restrictions.