Before our country’s measles vaccination program began in 1963, about 3 to 4 million Americans each year contracted measles, a highly contagious respiratory virus that can lead to acute swelling of the brain and cause permanent brain damage or even death. The campaign was a success, and by 2000 measles was thought to be eradicated in the United States.
But in March 2024, the Chicago Department of Public Health (CDPH), working with the Centers for Disease Control and Prevention (CDC), confirmed that a child living in a temporary shelter for migrants had the disease. Ultimately, 57 people were diagnosed with the illness—all of whom lived or worked at the shelter or had ties to those who did. Of those infected, nearly 75 percent were found to be unvaccinated.
Working with state and local health departments, the Chicago Department of Public Health worked with CDC to quickly investigate the outbreak and launch a mass vaccination campaign at the shelter. To deliver culturally and linguistically accessible messaging about measles infection and the importance of vaccination and quarantine, Chicago health officials collaborated with trusted community health workers and leaders, including Spanish-speaking “promotores de salud,” who possessed insight and understanding of the community served. Over three days, the campaign vaccinated 882 shelter residents and confirmed that 784 others were already vaccinated. By the campaign’s end, 93 percent of the shelter’s population were immunized, and the outbreak was checked.
The Chicago measles outbreak illustrates the importance of swift, coordinated public health responses in preventing the broader transmission of dangerous infectious diseases—a fight public health professionals wage every day across the United States and around the world.