Public health officials are sounding an urgent alarm over a critical decline in immunization rates across the Americas, warning that the resurgence of preventable diseases threatens to erase decades of medical progress. The trend is particularly concerning as the region prepares for major international sporting events, which are expected to increase global travel and the subsequent risk of pathogen transmission.
The crisis is most evident in the rise of zero-dose children
—those who have received no vaccinations. According to data from the World Health Organization (WHO) and the United Nations Children’s Fund (UNICEF), 1,465,000 children in the Americas did not receive the vaccine against diphtheria, pertussis (whooping cough), and tetanus in 2024. This gap in coverage severely compromises herd immunity and leaves populations vulnerable to outbreaks of diseases that were previously controlled or eliminated.
Measles, one of the most contagious viruses known, has seen a dramatic spike in the region. The Pan American Health Organization (PAHO) reported 14,767 confirmed cases across 13 countries in 2025, a figure nearly 32 times higher than the total recorded in 2024. This upward trajectory has continued into the current year; as of April 5, 2026, more than 15,300 cases have already been reported, surpassing the entire total for 2025.
“The reemergence of measles in the Americas is a significant setback, but completely reversible, which requires decisive action.” Jarbas Barbosa, Director of PAHO
The clinical impact of this decline is severe. PAHO noted that 93% of those infected with measles were unvaccinated, and approximately 13% of cases required hospitalization. Beyond a simple rash, measles can lead to life-threatening complications, including encephalitis, pneumonia, blindness, and death.
The scale of the current immunization gap is staggering. Leticia Belmont, president of the Mexican Academy of Pediatrics, noted during a vaccine seminar that the number of children missing essential vaccines in 2024 is equivalent to more than 17 full soccer stadiums of unprotected minors. She emphasized that increasing coverage is the only way to ensure that diseases do not become unwanted guests
at the year’s upcoming sporting events.
These current challenges stand in stark contrast to the historical success of immunization. According to PAHO, child vaccination in the Americas has prevented approximately 15 million deaths in children under 5, more than 1.1 billion cases of disability, and nearly 28.4 billion episodes of illness over the last half-century.
The current situation underscores a precarious moment for public health, where the failure to maintain routine vaccination schedules could lead to a permanent return of preventable childhood illnesses.
