This summer, travelers should be aware of new guidance from the CDC. The agency has alerted health departments nationwide to prepare for a potential increase in measles cases, as the warmer months typically lead to more travel and gatherings, creating ideal conditions for the virus to spread. The CDC noted, "With ongoing measles transmission in various regions of North America and anticipated rises in both international and domestic travel, as well as large events during spring and summer, we expect additional measles cases in the upcoming months."
As summer approaches, the statistics are alarming. By April 23, the CDC reported 1,792 confirmed measles cases in the United States for the year, following a troubling 2025, which saw 2,288 confirmed cases—the highest in decades. Of these, 2,263 cases were reported across 44 states, while the remaining 25 were linked to international visitors. Notably, 93% of those infected last year were either unvaccinated or lacked documented vaccination history, highlighting a significant vulnerability in the population.
Measles was declared eliminated in the U.S. in 2000, a significant achievement resulting from extensive vaccination efforts. However, this status is now under threat. CDC statistics reveal that vaccination rates among kindergartners have decreased from 95.2% during the 2019-2020 school year to 92.5% in 2024-2025. While this may seem minor, it represents a critical gap in herd immunity against one of the most contagious diseases. Dr. Bruce Farber, Chief of Public Health and Epidemiology at Northwell Health, expressed concern, stating, "To be honest, I think we have lost our elimination status already. How can you say we're measles-free when we're seeing measles?"
Measles is highly contagious and can spread through the air. The virus can remain airborne for up to two hours after an infected person coughs or sneezes. Infection can occur by touching contaminated surfaces and then touching the face. Symptoms typically appear between seven and 14 days post-exposure and include high fever, cough, runny nose, and watery eyes. For unvaccinated individuals, the risk of hospitalization is significant, with the CDC estimating that about one in five unvaccinated Americans who contract measles will need hospital care.
Fortunately, prevention is straightforward. The two-dose MMR vaccine is 97% effective, and individuals born before 1957 are generally considered to have natural immunity, as most would have contracted the disease in childhood.
The CDC's guidance issued on April 27 outlines specific expectations for public health departments. Officials are urged to meticulously document each confirmed case, track close contacts, and identify locations visited by infectious patients. Active surveillance is essential to quickly identify suspected cases and expedite laboratory testing.
Additionally, the agency recommends outreach to communities with lower vaccination rates and suggests utilizing state surveillance systems to monitor patterns of fever and rash illnesses that could indicate emerging clusters.
As summer nears and mobility increases, conditions are favorable for the continued spread of measles. While the CDC is not forecasting a worst-case scenario, it is advising health departments to prepare for one. Individuals uncertain about their or their children's MMR vaccination status should consider checking now.
