Missouri health officials have issued a warning regarding a potential measles exposure at Busch Stadium and several St. Louis-area businesses. The Missouri Department of Health and Senior Services (MDHSS) stated that the possible exposures occurred between September 12 and September 14.

This alert is part of a broader concern about measles transmission, with this incident being the third case linked to train exposure in Missouri. Health officials are urging anyone who may have been exposed to monitor for symptoms and take appropriate precautions.

The identified locations in St. Louis and the wider county include various local establishments. Among the places with potential exposure were local bars, a cafe, a restaurant, a sandwich shop, a grocery store, and a convenience store. Health authorities advise that individuals who were present at these locations during the specified dates should watch for measles symptoms for 21 days following their last date of exposure.

Those who develop symptoms are strongly encouraged to contact their local public health agency. Furthermore, individuals who suspect they have measles should self-isolate and call their healthcare provider before visiting a clinic or hospital to prevent further spread. This proactive measure helps healthcare facilities prepare and take necessary isolation protocols.

This situation follows earlier measles-related alerts in Missouri. Earlier in September, the MDHSS announced a possible exposure at a train station in Sedalia after a vaccinated individual traveled on a Chicago-bound train. Shortly after, the St. Louis County Department of Public Health confirmed that a second individual, who also boarded the same train on August 27, had measles. This second individual was vaccinated and represented the first confirmed case in a county resident in two decades.

Dr. Kanika Cunningham, director of the Saint Louis County Department of Public Health, emphasized the importance of vaccination. "Vaccination is one of the most effective ways to protect ourselves, our families and our community from measles," she stated. She also encouraged residents to check their vaccination records and consult healthcare providers if they believe they have been exposed.

Nationally, measles cases are on the rise. According to the Centers for Disease Control and Prevention (CDC), over 3,400 measles cases have been reported across 45 states and Washington, D.C., in 2026. The CDC recommends a two-dose measles, mumps, and rubella (MMR) vaccine regimen for optimal protection, with the first dose given between 12-15 months and the second between 4-6 years old. While one dose offers 93% protection and two doses offer 97% protection, vaccination rates have reportedly declined in recent years.

Data indicates a dip in MMR vaccination rates among kindergartners for the 2025-2026 school year, with 92.4% receiving the vaccine, compared to 95.2% in the 2019-2020 school year before the COVID-19 pandemic. This trend raises concerns about community immunity and the potential for outbreaks.