The Los Angeles Times has created a series of data visualizations illustrating how measles spreads through populations with vaccination rates below 95 percent. For example, the visualizations show that California’s measles outbreak in 2014, which infected 131 people, occurred when less than 93 percent of the California population was vaccinated. After the outbreak, California lawmakers barred parents from opting out of vaccines due to personal beliefs, causing the state’s vaccination rate to rise to 97 percent in 2017. The higher vaccination rate has helped California limit its current measles outbreak to 45 cases, but roughly 70 percent of the cases have occurred in counties where 95 percent or less of kindergartners had received all their required immunizations in 2018.