In recent months, the United States has experienced a concerning increase in measles cases, with 23 confirmed cases identified since December 2023. In response to this surge, the Centers for Disease Control and Prevention (CDC) have issued an alert to clinicians, urging them to be vigilant about identifying and reporting potential measles cases. The CDC emphasizes the need to closely monitor patients presenting with a rash accompanied by fever and other measles symptoms, particularly those who have recently traveled to countries grappling with ongoing measles outbreaks.

Out of the 23 reported cases in the US, seven were directly imported by international travelers, while two separate outbreaks involved more than five cases each. The majority of these cases were found among unvaccinated children and teenagers. It is a recurring pattern in the US, where measles outbreaks tend to originate from unvaccinated or undervaccinated individuals who contract the infection during travel and subsequently spread it within unvaccinated or undervaccinated communities.

Globally, the rise in measles cases has become a significant concern as vaccination rates, particularly for the measles, mumps, and rubella vaccine (MMR), have declined in recent years due to disruptions caused by the pandemic and vaccine hesitancy driven by misinformation. The CDC's recent outreach message highlights that the increase in measles importations aligns with the surging global measles cases, presenting a growing threat worldwide.

The World Health Organization (WHO) revealed alarming statistics regarding the European region's measles cases in 2023, reporting a more than 40-fold rise compared to the previous year. With over 42,200 measles cases recorded in the region last year, Kazakhstan, in particular, witnessed the highest incidence, reporting 13,677 cases. The outbreak in Kazakhstan has mainly been fueled by unvaccinated children who missed their routine immunizations during the pandemic. To combat the outbreak, the country is now focusing on catching up with vaccination schedules for children.

Other countries around the globe are also experiencing measles outbreaks. The UK Health Security Agency recently warned of a potential ongoing measles outbreak, with 216 confirmed cases and 103 probable cases reported in the West Midlands region since October 2023. Low MMR vaccination rates in certain areas increase the risk of further outbreaks.

While the majority of Americans have received their MMR vaccines on schedule, it is essential to highlight the high risk faced by unvaccinated and undervaccinated individuals if exposed to the measles virus. The CDC notes that the virus remains airborne for up to two hours after an infected person leaves an area and has an alarming infectivity rate of up to 90% for unvaccinated individuals. Measles is highly contagious, and individuals typically remain infectious for four days before and after the appearance of the telltale rash.

In light of these rising concerns and the global surge in measles transmission, health organizations like the CDC and WHO are emphasizing the importance of measles vaccination. They urge individuals, especially those who have not received the recommended doses of the MMR vaccine, to prioritize their immunizations to protect themselves and prevent the further spread of this highly infectious disease.