US faces measles cliff as vaccination rates fall, researchers warn
CDC says current outbreak already the second-highest in 25 years as concern mounts that the disease could once again become endemic
24 April 2025 - 22:29
byNancy Lapid
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A measles alert sign in New York, the US, March 14 2025. Picture: REUTERS/SHANNON STAPLETON
New York — The US is at a tipping point for the return of endemic measles 25 years after the disease was declared eradicated in the country, researchers warned on Thursday.
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%, about 11.1-million cases of measles would result over 25 years, according to a report of the study in the peer-reviewed medical journal JAMA.
Measles has not been endemic, or continuously present, in the US since 2000.
With vaccination rates dropping for MMR shots, as well as for 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, including 624 cases and two deaths in one Texas outbreak, according to the Centers for Disease Control and Prevention.
Total US measles cases to April 17 represent an increase of about 180% 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 issued on Thursday.
If vaccination rates go 5% lower, you’ll have tens of thousands of infected patients.
Mujeeb Basit associate director of the Clinical Informatics Center
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% of cases were in people who were unvaccinated or whose vaccination status was unknown.
Many state and national policies are being debated that may substantially reduce childhood vaccination even further, said 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.
Robert F Kennedy Jnr, who now heads the department of health and human services, has for decades helped sow such doubts, which accelerated during the Covid-19 pandemic as vaccines for that virus became a political issue.
Drawing on state vaccination, birth and death data and historical data on measles infections, researchers simulated a population that mirrors that of the US 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%, 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, Lo said.
Under that scenario, Lo 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 admissions to hospital, and 159,200 deaths.
Small increases in vaccination rates of about 5% could keep measles from becoming endemic, the researchers’ models suggest.
Alarming trend
Under current levels of vaccination, vaccine-preventable diseases other than measles are unlikely to become endemic, Lo said. But if vaccination rates drop by 35%, rubella is likely to 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%.
No-one can forecast exact vaccination and infection numbers, but the precise numbers don’t matter, said Mujeeb Basit, associate director of the Clinical Informatics Center at UT Southwestern Medical Center, who was not involved in the research.
What matters, 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% lower, you’ll have tens of thousands of infected patients,” he said.
“Rates just have to be 15% less and you’re at millions of cases,” he added. “The trend is what people need to know.”
Support our award-winning journalism. The Premium package (digital only) is R30 for the first month and thereafter you pay R129 p/m now ad-free for all subscribers.
US faces measles cliff as vaccination rates fall, researchers warn
CDC says current outbreak already the second-highest in 25 years as concern mounts that the disease could once again become endemic
New York — The US is at a tipping point for the return of endemic measles 25 years after the disease was declared eradicated in the country, researchers warned on Thursday.
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%, about 11.1-million cases of measles would result over 25 years, according to a report of the study in the peer-reviewed medical journal JAMA.
Measles has not been endemic, or continuously present, in the US since 2000.
With vaccination rates dropping for MMR shots, as well as for 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, including 624 cases and two deaths in one Texas outbreak, according to the Centers for Disease Control and Prevention.
Total US measles cases to April 17 represent an increase of about 180% 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 issued on Thursday.
associate director of the Clinical Informatics Center
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% of cases were in people who were unvaccinated or whose vaccination status was unknown.
Many state and national policies are being debated that may substantially reduce childhood vaccination even further, said 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.
Robert F Kennedy Jnr, who now heads the department of health and human services, has for decades helped sow such doubts, which accelerated during the Covid-19 pandemic as vaccines for that virus became a political issue.
Drawing on state vaccination, birth and death data and historical data on measles infections, researchers simulated a population that mirrors that of the US 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%, 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, Lo said.
Under that scenario, Lo 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 admissions to hospital, and 159,200 deaths.
Small increases in vaccination rates of about 5% could keep measles from becoming endemic, the researchers’ models suggest.
Alarming trend
Under current levels of vaccination, vaccine-preventable diseases other than measles are unlikely to become endemic, Lo said. But if vaccination rates drop by 35%, rubella is likely to 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%.
No-one can forecast exact vaccination and infection numbers, but the precise numbers don’t matter, said Mujeeb Basit, associate director of the Clinical Informatics Center at UT Southwestern Medical Center, who was not involved in the research.
What matters, 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% lower, you’ll have tens of thousands of infected patients,” he said.
“Rates just have to be 15% less and you’re at millions of cases,” he added. “The trend is what people need to know.”
Reuters
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