Some Baltimore City students still aren’t vaccinated against childhood diseases. It could become a costly problem for the district.

Every public school in the state on Friday morning will take an official count of how many students are sitting in their classrooms, a crucial annual census that will be used to determine how much money school systems and individual campuses will receive from the state and federal governments next year. Not counted will be children whose parents don’t have health insurance and can’t afford to have their kids immunized against standard childhood diseases, such as mumps and measles, quickly. The Baltimore City health department, which has held free clinics for vaccinations, has no available appointments for weeks.