In 2005, a 17-year-old girl whose family belonged to a church that discouraged vaccination went on a mission trip to Europe. The day after the group arrived home, the church threw a party; 34 attendees caught measles from the teen or from someone she infected. Not including medical care, containing that outbreak cost $167,685. When they analyzed the spending, the CDC and the state health department calculated it had taken 3,650 work hours, 4,800 phone calls, and 5,500 miles of car trips to track the victims down. In 2008, an unvaccinated infected traveler brought measles to a hospital in Tucson; the cost of containing the outbreak, which spread to a second hospital, was almost $800,000.

The numbers can grow much bigger still. Researchers at the CDC estimated that handling 107 cases of measles that occurred in 2011 cost state and local health departments between $2.7 million and $5.3 million. In 2014, 42 people came down with the disease after passing through Disneyland at the same time as a never-identified person with measles—and subsequently infected 90 additional people in California, 14 more in other states, and a further 159 people in Canada. The cost of controlling the outbreak, just in California, totaled almost $4 million. And in 2017, a five-month outbreak of measles in Minnesota infected 79 people and cost the state $2.3 million.