A significant measles outbreak in the United States is raising alarm bells for public health officials on both sides of the Atlantic, particularly as millions of Americans prepare to travel for the holiday season. The highly infectious disease, declared eliminated in the US in 2000, has now infected 1,958 people and caused three deaths this year alone.
State-by-State Surge in Infections
Recent data reveals a sharp and concerning rise in cases across multiple states. In Utah County, health officials confirmed six new cases this week in individuals aged 18 and under, bringing the state's total to 142 confirmed infections. This marks a dramatic increase from just one case in 2023 and none in 2024 prior to the outbreak.
The profile of those infected is telling: of Utah's 142 cases, 127 were unvaccinated, eight were vaccinated, and seven have an unknown vaccination status. Furthermore, 85 cases are in patients under 18, with 14 requiring hospitalisation.
Other states are experiencing similar crises. South Carolina has also recorded 142 cases, leading to more than 250 people being quarantined due to possible exposure. Arizona has seen cases surge from five in 2024 to 182 this year. Connecticut reported its first case since 2021 last week.
Falling Vaccination Rates Fuel Outbreaks
Health experts are unequivocal in identifying the root cause: declining childhood immunisation rates. Dr Renee Dua, a medical advisor, stated: 'The current measles outbreaks in the US are a direct consequence of falling childhood vaccination rates.'
Measles requires a community immunity threshold of approximately 95% to prevent its spread, a target many regions are now failing to meet. While the national MMR vaccination rate stands at 92.5%, key outbreak states are below this:
- Utah: 89% of kindergarteners vaccinated (2023-2024).
- Arizona: 89%.
- South Carolina: 92%.
The CDC states the MMR vaccine is 97% effective with two doses. Of the current national cases, 93% are in people who are either unvaccinated or have an unknown vaccine status.
Holiday Travel and Public Health Warnings
With the holiday travel period imminent, epidemiologists are deeply concerned about further spread. Dr Jodie Guest, senior vice chair of epidemiology at Emory University, warned: 'Most of us, including viruses, are not contained by state lines. This is an incredibly transmissible virus.'
She advised those planning to travel or host guests from outbreak areas to inquire about possible measles exposure. While vaccinated individuals have strong protection, she urged caution for the unvaccinated considering travel to high-risk regions.
The scale of the outbreak is now the largest since 1992, when 2,126 cases were reported. Nationally, the virus has hit children hardest, with 512 cases in under-5s and 808 in 5- to 19-year-olds. 222 patients have been hospitalised, with 20% of those being children under five.
Measles is caused by a virus that leads to flu-like symptoms and a distinctive rash. Severe complications can include pneumonia, seizures, and encephalitis (brain swelling), which can cause permanent damage or death. Before the two-dose vaccine was introduced in 1968, the US saw up to 500 measles deaths annually.
Dr Dua concluded with a stark message: 'We are seeing real consequences: preventable outbreaks, hospitalisations, and deaths... Vaccines remain among the safest and most effective tools in medicine.' The situation underscores the critical need for maintaining high vaccination coverage to protect public health.
