Even a 10% decline in vaccination rates would cause cases to skyrocket, leading to massive increase in demand for clinical laboratory MMR testing
As policymakers consider revisions to the current childhood vaccination schedule, a simulation model developed at Stanford University projects that declines in vaccination rates could lead to a dramatic resurgence of measles and other preventable infectious diseases over the next 25 years. Even at current vaccination rates, measles could once again become endemic in the US within two decades, the researchers reported.
The model suggests that clinical laboratories could one day find themselves testing millions of children for diseases once thought to be nearly eliminated in the US.
“With measles, we’re right on the cusp,” said senior author Nathan Lo, MD, PhD, assistant professor of infectious diseases, in a Stanford Medicine press release. “Increasing vaccination levels by just 5% brings the number of measles cases down, safely away from returning to endemic levels.”
“We’ve seen a worrisome pattern of decreasing routine childhood vaccinations,” said study senior author Nathan Lo, MD, PhD, in a Stanford Medicine press release. (Photo copyright: Stanford University.)
Millions of Measles Cases Predicted if Vaccinations Drop
To complete their study, the researchers looked at four infectious diseases:
“We used a large-scale epidemiological model to simulate all individuals living in the US and assigned them an age, vaccination status, immunity, state of residence, etc.,” Lo explained. “We then simulated how infections would spread under different vaccine conditions.”
Each state was modeled independently to account for variations in risk, noted lead author Mathew Kiang, ScD, assistant professor in the department of epidemiology and population health at Stanford. For example, Massachusetts is considered low risk due to high vaccination rates, whereas Texas and California are “higher risk because vaccination rates in both have dropped and there’s a lot of travel to those states,” he said.
The model assumed that infections would not cross state lines, “so the numbers could be an underestimate,” Kiang said.
He painted a grim picture of the scenarios projected by the model.
“If vaccination were to fall by even 10% today, measles cases would skyrocket to 11.1 million over the next 25 years,” he said. “If vaccination rates were cut in half, we’d expect 51.2 million cases of measles, 9.9 million cases of rubella, 4.3 million cases of polio, and 200 cases of diphtheria over 25 years. This would lead to 10.3 million hospitalizations and 159,200 deaths, plus an estimated 51,200 children with post-measles neurological complications, 10,700 cases of birth defects due to rubella, and 5,400 people paralyzed from polio.”
Lo suggested a more hopeful scenario in which “some fraction of the unvaccinated population seeks vaccination” as the diseases spread over the next decade. However, “if that were to happen, you can’t just flip a switch—once these diseases get unleashed, it would take time eliminate them again,” he said.
As of May 22, 2025, 1,046 cases of measles have been reported in the US this year, according to the Centers for Disease Control and Prevention. This year has been among the most active for measles since 2000. For the whole of 2024, 285 cases were reported.
More Contagious than COVID-19
All four diseases are far more contagious than COVID-19, Lo said, but measles “is in a different ballpark” as one of the most infectious diseases known to medicine. In a fully susceptible population, he said, one person can infect up to 20 individuals, but for the purposes of the simulation, they used a more conservative estimate of 12.
“There was a disruption to healthcare services during the pandemic, but declines preceded this period and have accelerated since then for many reasons,” he noted. “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.”
Another concern with measles is that the MMR vaccine “has become particularly controversial, partly due to a history of fraudulent medical research that raised safety concerns,” Lo said.
He added that compared to the other diseases, measles is more prevalent globally.
“Travelers importing a disease are like matches, and US under-vaccination is the tinder,” Kiang said. “With measles, you’re throwing a lot of matches in, and eventually something is going to happen.”
Experts say it is time ‘to restore our confidence in vaccines’ as many medical laboratories take steps to support testing for the polio virus
Clinical laboratories and microbiologists in the state of New York will want to know that, in July, a man in New York was diagnosed with polio and subsequently the virus was detected in the wastewater of two New York counties.
The area, Rockland County, N.Y., just north of New York City, was also at the forefront of a measles outbreak that occurred in 2018 and 2019. The outbreak was attributed to low vaccination rates within the community.
The unidentified, immunocompetent young man was admitted to a New York hospital after experiencing a low-grade fever, neck stiffness, back and abdominal pain, constipation, and lower extremity weakness. He eventually developed paralysis from the disease, which is irreversible.
Poliomyelitis, commonly known as polio, is a disabling and life-threatening disease that is caused by the poliovirus. Though it rarely surfaces in the United States, there is now confirmation of the first US case since 2013.
“The polio vaccine is safe and effective, protecting against this potentially debilitating disease, and it has been part of the backbone of required, routine childhood immunizations recommended by health officials and public health agencies nationwide,” said Mary T. Bassett, MD (left), Health Commissioner at the New York Department of Health, in a press release. Clinical laboratories and microbiologists in New York may want to prepare for an increase in vaccination requests. (Photo copyright: Time.)
Is Polio Back in America? Clinical Laboratories Will Want to Be Prepared
“I think it’s concerning because it can spread,” epidemiologist Walter Orenstein, MD, Professor, Department of Medicine, Division of Infectious Diseases at Emory University School of Medicine told STAT. “If there are unvaccinated communities, it can cause a polio outbreak.”
According to the federal Centers for Disease Control and Prevention (CDC), public health experts are working diligently to discover how and where the infected individual contracted polio. The CDC website states that the risk for people who have received the polio vaccine is very low, but there is concern for those who have not received the recommended doses of the vaccine.
“Most of the US population has protection against polio because they were vaccinated during childhood, but in some communities with low vaccine coverage, there are unvaccinated people at risk,” the CDC noted. “Polio and its neurologic effects cannot be cured but can be prevented through vaccination.”
The US uses an injectable polio vaccine for the poliovirus which contains killed viruses. The vaccine “instructs” the immune system to recognize and combat the virus. This inactivated polio vaccine (IPV) is administered to children as a shot in the arm or leg and is typically given in four separate doses.
“The inactivated polio vaccine we have is very effective and very safe and could have prevented this,” Orenstein told STAT. “We need to restore our confidence in vaccines.”
“Based on what we know about this case, and polio in general, the (New York) Department of Health strongly recommends that unvaccinated individuals get vaccinated or boosted with the FDA-approved IPV polio vaccine as soon as possible,” said Mary T. Bassett, MD, Health Commissioner at the New York Department of Health in a press release.
Poliovirus Found in Wastewater via Use of Gene Sequencing
Poliovirus is very contagious and is transmitted through person-to-person contact. The virus lives in an infected person’s throat and intestines and can contaminate food and water in unsanitary conditions. According to the CDC, typical symptoms of the illness include flu-like symptoms such as:
Sore throat
Fever
Tiredness
Nausea
Headache
Stomach pain
Most of these symptoms will disappear within five days, but polio can invade the nervous system and cause more serious complications, such as meningitis, paralysis, and even death.
After confirmation of the new case of polio, wastewater surveillance detected the presence of the poliovirus in Rockland and Orange counties, New York.
Wastewater analysis can uncover pathogens within a community and has been used in the fight against other infectious diseases, including:
“In some regards, wastewater is a public health dream scenario,” said Mark Siedner, MD, an infectious disease doctor at Massachusetts General Hospital and associate professor at Harvard Medical School, in an interview with Fortune. “Everyone poops, and most people poop every day. It provides real-time data on infection rates. In that regard, it’s an extremely powerful tool, particularly good at detecting early warning signs. Before people get sick, we might get a signal.”
Wastewater analysis can provide insights regarding the types of viruses that people within a community are shedding and if the volume of those viruses are increasing. This information can provide scientists with an early marker for an outbreak of an illness that is on the verge of spreading.
Microbiologists and clinical laboratories should be aware of the specific types of infectious agents public health authorities are detecting in wastewater, even as they perform screening and diagnostic tests on their patients for similar infectious diseases.
Polio is Appearing Worldwide
The Global Polio Eradication Initiative (GPEI) has announced that new cases of polio have been reported in Israel and the United Kingdom. These are countries where polio cases are extremely rare.
This indicates that microbiologists and clinical laboratories managers will want to be on constant alert for uncommon infectious diseases that may appear suddenly, even if those illnesses are rare. Accurate and immediate diagnoses of such infectious diseases could play a major role in triggering a public health response to control potential outbreaks while they are in their earlier stages.
