What Happened to Measles?

Measles, a highly contagious viral disease, has historically been a major cause of childhood mortality worldwide. The introduction of the measles vaccine in 1963 and subsequent widespread immunization campaigns led to a dramatic reduction in cases and deaths, culminating in the declaration of measles elimination in the United States in 2000. However, this public health triumph has been severely challenged in recent years, with a significant global resurgence unfolding from 2020 through 2026.

The primary catalyst for this alarming comeback is a confluence of factors, most notably the decline in global vaccination coverage. The World Health Organization (WHO) and UNICEF reported that in 2024, only 84% of children received their first dose of the measles vaccine (MCV1) and 76% received their second dose (MCV2), falling well short of the 95% coverage needed to achieve herd immunity and prevent outbreaks. This immunity gap has created a susceptible population, allowing the highly transmissible virus to spread rapidly. The COVID-19 pandemic played a critical role in exacerbating this decline, causing widespread disruptions to routine immunization services and leading to the postponement of mass vaccination campaigns in many countries. Millions of children missed their scheduled doses, creating a growing pool of unvaccinated individuals vulnerable to infection.

Compounding the issue is a rise in vaccine hesitancy and the spread of misinformation, particularly through social media. This skepticism about vaccine safety and effectiveness has eroded public trust in health authorities and contributed to lower vaccination rates in various communities. In the United States, for instance, the average county-level measles vaccination rate fell from 93.9% in 2019 to 91.3% in 2024 among kindergartners. Weakened public health infrastructure, including funding and staffing cuts, has further hampered effective measles prevention and response efforts.

The consequences of these trends have been severe. Globally, an estimated 10.3 million people were infected with measles in 2023, and 95,000 deaths occurred in 2024, predominantly among unvaccinated children under five. The number of countries experiencing large or disruptive measles outbreaks sharply increased to 60 in 2024, nearly doubling from 33 in 2022. In a significant setback, Canada lost its measles elimination status in November 2025 following prolonged outbreaks. Subsequently, the Pan American Health Organization (PAHO) announced that the Region of the Americas, which includes the United States, also lost its elimination status. In January 2026, the WHO confirmed that six countries in Central Asia and Europe—Armenia, Austria, Azerbaijan, Spain, the United Kingdom, and Uzbekistan—lost their elimination status based on 2024 data.

As of July 3, 2026, the situation remains critical. The United States has seen a dramatic surge in cases, with 2,288 confirmed cases in 2025, marking a 30-year high. The trend continues into 2026, with 2,170 confirmed cases reported across 41 jurisdictions as of July 2, 2026, with 93% of these cases occurring in unvaccinated or unknown-status individuals. This ongoing transmission puts the U.S. at direct risk of losing its individual elimination status, with PAHO scheduled to review it in November 2026. The global resurgence of measles underscores the fragility of public health achievements and the urgent need to address vaccination gaps, combat misinformation, and strengthen immunization programs worldwide.