Measles Was Eradicated in the US. How Did It Make a Comeback?

The eradication of measles in the United States was a significant public health achievement, but the disease has made a comeback in recent years. As of February 20, 2025, a total of 93 measles cases were reported by eight jurisdictions, with 92% of cases being outbreak-associated. This resurgence of measles can be attributed to several factors, including the decline in vaccination rates, the spread of misinformation and vaccine hesitancy, and the role of international travel in reintroducing the disease.

The decline in measles vaccination rates in the United States can be attributed to several factors. The spread of anti-vaccine messages and misinformation has fueled doubts and distrust towards vaccines, leading to delays in vaccine uptake. The COVID-19 pandemic has also played a significant role in exacerbating this trend, as the pandemic has led to disruptions in routine immunization services and a decrease in healthcare access. Additionally, the decline in vaccination rates can be attributed to the decrease in U.S. MMR coverage among kindergarteners, which is now below the 95% coverage target in many communities. This decline in vaccination rates has contributed to the resurgence of measles cases in the United States.

Global measles activity and international travel have significantly contributed to the reintroduction of measles in the United States. The World Health Organization (WHO) reports that measles cases have been increasing globally, with an estimated 10.3 million people infected with measles in 2023. This increased global activity means that unvaccinated or under-vaccinated individuals are more likely to contract measles abroad and bring it back to the United States. Unvaccinated international travelers have also contributed to the reintroduction of measles in the U.S., as measles cases and outbreaks are often linked to unvaccinated international travelers. Large measles outbreaks are possible when travel-related measles cases reach at-risk U.S. populations with low immunization against measles.

The COVID-19 pandemic has played a significant role in exacerbating challenges in surveillance and immunization efforts, leading to an increase in measles cases. The pandemic has led to the closure of health facilities and the diversion of resources to combat COVID-19, resulting in a decline in routine immunization services. This disruption has led to a decrease in vaccination rates, making populations more susceptible to measles outbreaks. The pandemic has also contributed to the spread of misinformation and vaccine hesitancy, as anti-vaccine messages and false information have fueled doubts and distrust towards vaccines, leading to delays in vaccine uptake. The pandemic has also led to a decrease in surveillance and reporting of measles cases, as health systems were overwhelmed with COVID-19 cases, and resources were redirected, leading to underreporting of measles cases.

In conclusion, the resurgence of measles in the United States can be attributed to several factors, including the decline in vaccination rates, the spread of misinformation and vaccine hesitancy, and the role of international travel in reintroducing the disease. The COVID-19 pandemic has exacerbated these challenges, leading to an increase in measles cases. To prevent further outbreaks, it is crucial to address these challenges and strengthen immunization programs to achieve regional elimination goals.