Measles outbreaks in the USA: Danger increases due to declining vaccination rates

Stanford. In the United States, declining vaccination rates among children could lead to diseases like measles becoming more common again and becoming persistent in the population. This would increase the risk of severe outbreaks – even in regions where measles has been largely under control. This is the conclusion of a new study by researchers at the Stanford Medicine Institute and other universities, published in the Journal of the American Medical Association (JAMA).

Using a computer model, the research team simulated how measles, rubella, polio, and diphtheria would spread under different vaccination conditions. They considered data on population trends, existing immunity in the population, and the risk of infectious diseases being imported. Current vaccination rates are based on figures from 2004 to 2023.

Even with current vaccination rates, researchers predict that measles could recur regularly in the next 20 years – with approximately 850,000 cases, 170,000 hospital admissions, and 2,500 deaths in 25 years. "If vaccinations were to decline by even just ten percent today, measles cases would rise to 11.1 million in the next 25 years," predicts the study's lead author, Mathew Kiang.

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If vaccination rates continue to decline over a prolonged period, measles and other diseases considered eradicated in the United States—such as rubella and polio—could resurface. "If vaccination rates were halved, 51.2 million cases of measles, 9.9 million cases of rubella, 4.3 million cases of polio, and 200 cases of diphtheria would be expected within 25 years. This would result in 10.3 million hospitalizations and 159,200 deaths," warns Kiang.

At the same time, lead author of the study, Nathan Lo, emphasizes: "Increasing vaccination rates by five percent could already prevent measles from circulating permanently again." The problem is that, at least since the coronavirus pandemic, but also before, the number of routine vaccinations has declined. Lo describes: "People are looking around and saying, 'We don't see these diseases. Why should we get vaccinated against them?'" There is a general vaccine hesitancy as well as "distrust and misinformation about the efficacy and safety of vaccines."

Parts of a measles virus under the electron microscope.

Source: Cynthia Goldsmith/dpa

The topic of measles recently sparked renewed public debate in the United States because, for the first time in ten years, two children in Texas died of measles—they were unvaccinated. In addition, there were several hundred infections nationwide, most of them in Texas. Most of those affected were unvaccinated.

In light of this development, Secretary of Health Robert F. Kennedy Jr., appointed by US President Donald Trump, declared vaccination the most effective method to prevent the spread of measles. Initially, however, in interviews, he had referred to vitamin A and cod liver oil as remedies in light of the measles epidemic. In previous years, he had also expressed doubts about the usefulness of vaccinations. This, too, led to considerable criticism of his appointment as Secretary of Health.

According to the Robert Koch Institute (RKI), the number of registered measles cases in Germany fluctuates from year to year. From 2012 to 2023, the number was at a low of just eight cases in the pandemic year of 2021. In 2015, the highest number of cases during this period was 2,466.

The EU health authority ECDC registered ten deaths related to measles in 2024, nine of them in Romania and one in Ireland. According to the World Health Organization (WHO), there were an estimated 107,000 such deaths worldwide in 2023, most of them among unvaccinated or undervaccinated children under five years of age.

Measles is transmitted from person to person through droplets, for example, when coughing, sneezing, or talking. Almost any contact leads to infection if someone is unvaccinated. Only a double vaccination offers reliable protection. Infected individuals are contagious as early as five days before the typical red rash appears. Flu-like symptoms such as high fever, cough, and runny nose are followed by the rash days later.

Measles weakens the immune system. Bronchitis, middle ear infections, or pneumonia can result, and rarely, encephalitis. Up to 20 percent of those affected die from this. Almost one-third suffer severe sequelae such as mental retardation or paralysis. There is no specific antiviral therapy for measles.

RND/dpa