The share of U.S. counties where 95 percent or more of kindergartners were vaccinated against measles — the number doctors say is needed to achieve overall protection for the class, known as “herd immunity” — has dropped from 50 percent before the pandemic to 28 percent, according to The Post’s examination of the public records from 44 states and the District of Columbia.

Access options:

• gift link — registration required
• archive.today — has text, but interactive map with school-specific vaccination rate information and graphics do not work