On Apr. 24, 2014, the U.S. Centers for Disease Control and Prevention (CDC) estimated that vaccinations prevent more than 21 million hospitalizations and 732,000 deaths among children born in the last 20 years. Despite the U.S. immunization program’s success, according to CDC officials, 129 people in the U.S. were reported to have had measles in 13 outbreaks, as of Apr. 18, 2014.

In 1994, the Vaccines for Children program (VFC) was launched in direct response to a measles resurgence in the United States that caused tens of thousands of cases and over a hundred deaths, despite the availability of a measles vaccine since 1963. The VFC program provides vaccines to children whose parents or caregivers might otherwise be unable to afford them.

This year’s 20th anniversary of the VFC program’s implementation is occurring during an increase in measles cases in the U.S. In 2013, 189 Americans had measles. In 2011, 220 people in the U.S. were reported as having measles–the highest number of annual cases since 1996.