Measles could be well positioned for a comeback in the United States in a very short period of time. If immunization rates continue to drop for a prolonged period of time, the US could see millions of measles cases over the next 25 years. Other diseases not widely seen in the US, including polio and rubella could also become more prevalent, but not endemic. The study was published April 24 in the Journal of the American Medical Association.
Despite their success, childhood vaccination rates are falling in the US, largely fueled by misinformation, conspiracy theories, and public health disruptions due to the COVID-19 pandemic. Lower levels of immunity have already resulted in a recent outbreak in western Texas that has killed two children, infected more than 620 people, and hospitalized 64 others.
“We’ve seen a worrisome pattern of decreasing routine childhood vaccinations,” Dr. Nathan Lo, a study co-author and infectious disease expert at Stanford Medicine, said in a statement. “There was a disruption to health care services during the pandemic, but declines preceded this period and have accelerated since then for many reasons. People look around and say, ‘We don’t see these diseases. Why should we vaccinate against them?’ There’s a general fatigue with vaccines. And there’s distrust and misinformation about vaccine effectiveness and safety.”
The new study used large-scale epidemiological modeling to simulate how infectious disease would spread in the US at various childhood vaccination levels. Even at current immunization rates, the authors predict that measles may become endemic again and be circulating in the US within only 20 years. However, small increases in vaccine coverage would prevent this.
“For current rates, we took a conservative approach by using average vaccination levels between 2004 and 2023,” Matthew Kiang, a study co-author and epidemiologist also with Stanford Medicine, said in a statement. “With measles, we found that we’re already on the precipice of disaster. If vaccination rates remain the same, the model predicts that measles may become endemic within about 20 years. That means an estimated 851,300 cases over 25 years, leading to 170,200 hospitalizations and 2,550 deaths. The other diseases are not likely to become endemic under the status quo.”
Before the measles vaccine was introduced in 1963, the Centers for Disease Control and Prevention estimates that 3 million to 4 million people in the United States were infected each year. Of those, 400 to 500 people died, 48,000 were hospitalized, and 1,000 suffered swelling of the brain–or encephalitis.
With these declining vaccination rates, the study authors believe that measles could become endemic since it is one of the most infectious diseases that exists. One person can infect up to 20 others. While polio, diphtheria, and rubella are more infectious than COVID-19, “measles is in a different ballpark,” according to Lo.
[ Related: The shaky science behind treating measles with vitamin A. ]
“Also, the MMR (measles, mumps and rubella) vaccine has become particularly controversial, partly due to a history of fraudulent medical research that raised safety concerns; it has been conclusively shown that there is no link with autism,” said Lo. “Measles is also more common around the world, so travelers are more likely to bring it back.”
Increasing vaccination rates by just five percent would likely bring the number of measles cases away from endemic levels. With that, the authors encourage parents to discuss vaccinations with their pediatrician.
“It’s worth emphasizing that there really shouldn’t be any cases at this point, because these diseases are preventable,” said Kiang. “Anything above zero is tragic. When you’re talking about potentially thousands or millions, that’s unfathomable.”
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