US at tipping point for return of endemic measles
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A measles advisory is tacked to a bulletin board outside Gaines County Courthouse on April 9 in Seminole, Texas. The state has seen two deaths from the disease so far.
PHOTO: AFP
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WASHINGTON – The United States is at a tipping point for the return of endemic measles a quarter-century after the disease was declared eradicated in the country, researchers warned on April 24.
At current US childhood vaccination rates, measles could return to spreading regularly at high levels, with an estimated 851,300 cases over the next 25 years, computer models used by the researchers suggest.
If rates of vaccination with the measles-mumps-rubella, or MMR, shot were to decline by 10 per cent, an estimated 11.1 million cases of measles would result over 25 years, according to a report of the study in the Journal of the American Medical Association (Jama).
Measles has not been endemic, or continuously present, in the US since 2000.
With vaccination rates dropping for MMR shots as well as other childhood vaccines, outbreaks of preventable infectious diseases are increasing. There have been 10 reported outbreaks and at least 800 measles cases in the US so far in 2025,
Total US measles cases through April 17 represent about a 180 per cent increase over the 285 cases reported in all of 2024 – the second-highest annual US case count in 25 years, the CDC said in its weekly report on April 24.
The cases in the ongoing outbreak in Texas, New Mexico and Oklahoma have occurred among close-knit communities with low vaccination rates, according to the report. Overall, 96 per cent of cases were in people who were unvaccinated or had unknown vaccination status.
Many state and national policies are being debated that may substantially reduce childhood vaccination even further, said Assistant Professor Nathan Lo of Stanford Medical School, who led the Jama study.
The decline in vaccination among US children in recent years has been fuelled by promotion of theories – contrary to scientific evidence – that childhood vaccines are a cause of autism and other health risks.
Mr Robert F. Kennedy Jr, who now heads the US Department of Health and Human Services, has for decades helped sow such doubts, which accelerated during the Covid-19 pandemic with politicising of vaccines for that virus.
Drawing on state vaccination, birth and death data and historical data on measles infections, researchers simulated a population that mirrors the US population at national and state levels. Then they estimated how measles would spread under various scenarios if imported from a travelling US citizen who gets infected abroad.
If routine childhood vaccinations declined by 50 per cent, the country would see 51.2 million measles cases, 9.9 million rubella cases, and 4.3 million poliomyelitis cases over the next 25 years, Prof Lo said.
In this scenario, he said, there would be 51,200 patients with lasting neurologic side effects of measles, 10,700 birth defects resulting from congenital rubella infections, 5,400 cases of paralysis from polio, 10.3 million hospitalisations, and 159,200 deaths.
Small increases in vaccination rates of around 5 per cent could keep measles from becoming endemic, the researchers’ models suggest.
Troubling trend
Under current levels of vaccination, vaccine-preventable diseases other than measles are unlikely to become endemic, Prof Lo said. But if vaccination rates drop by 35 per cent, rubella will likely become endemic, while polio, which has long been eradicated in the US, has a 50-50 chance of making a comeback if vaccination drops by 40 per cent.
No one can forecast exact vaccination and infection numbers, but the precise numbers do not matter, said Dr Mujeeb Basit, associate director of the Clinical Informatics Centre at UT Southwestern Medical Centre, who was not involved in the research.
What matters, Dr Basit said, is the trend revealed by the study: As the vaccination rate declines, the rate of increase in measles cases speeds up.
“If vaccination rates go 5 per cent lower, you’ll have tens of thousands of infected patients,” he said.
“Rates just have to be 15 per cent less and you’re at millions of cases,” he added. “The trend is what people need to know.” REUTERS
