Measles: we’re on the precipice of a disaster, experts say
Measles may become endemic again within 20 years if vaccination rates don’t improve, according to new modelling.
Only 2 doses of the measles, mumps and rubella (MMR) vaccine are required to achieve 99 per cent effectiveness to prevent infection from the virus for life.
These are usually both administered to children by the age of six, and have drastically cut measles outbreaks in countries like Australia and the US in recent decades.
But as vaccine hesitancy and potential changing policy leads to a drop in vaccination coverage, measles is beginning to make a comeback.
Australia has recorded more than 50 measles cases so far in 2025, compared to 57 cases total for all of 2024. In the US, three people have already died from measles in 2025. Total case numbers have jumped from 285 in 2024 to 885 in 2025 so far.
But how will the size and frequency of disease outbreaks change if vaccination rates stay the same? What about if they continue to fall? Or improve?
A new study has used large-scale epidemiological modelling to answer these questions.
A Stanford University team in the US investigated four infectious diseases that had all been previously eliminated in the US by childhood vaccinations: measles, rubella, polio and diphtheria.
The model predicted possible pathways over the next 25 years, depending on vaccination rates.
“As vaccinations decline, the effect won’t be immediate,” says Stanford’s Mathew Kiang, lead author on the paper published in JAMA.
“We wanted to know: when will we see the impact of decisions being debated and made now?” Kiang said.
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The findings are vastly contrasting, and some pathways are devastating. But the outcome depends on actions taken now.
The predictions
The model looked at how each of the four diseases would spread if brought back to the US from another country.
“Right now, so many people are immune through vaccination that diseases don’t spread far,” says co-author Nathan Lo, an infectious diseases researcher also from Stanford. “But if vaccinations decline over a longer period, you start to see outbreaks increase in size and frequency.
“Eventually, you see sustained, ongoing transmission, meaning these diseases become endemic – they become household names once again,” Lo said.
The model predicts that if vaccine coverage and public health responses don’t improve, measles could become endemic again within two decades.
“That means an estimated 851,300 cases over 25 years, leading to 170,200 hospitalisations and 2550 deaths,” Kiang said.
Meanwhile, a mere 5 per cent increase in MMR vaccinations could cut cases to under 6000 and prevent measles from becoming endemic.
However, if MMR vaccinations decline by 10 per cent, then the model estimates that case numbers will soar to 11.1 million over 25 years.
A decline in MMR vaccinations could see cases soar. Photo: Getty
“While the effects of declining vaccination won’t be immediate, we could eventually see the return of awful complications from diseases that most clinicians today have not encountered thanks to decades of successful immunisation,” Lo said.
The researchers note that out of all the diseases studied, measles is the most likely to become endemic.
“Measles is one of the most infectious diseases that exists, so the number of people who have to be immune to prevent it from spreading is extremely high,” Lo explains.
“Also, the MMR 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.”
The model also examined other potential scenarios where vaccine-preventable diseases surge. For example, if vaccinations rates were cut in half, over a 25-year period this could result in:
- 51.2 million measles cases (where the disease becomes endemic in less than 5 years’ time)
- 9.9 million rubella cases
- 4.3 million poliomyelitis cases
- 197 diphtheria cases
- 10.3 million hospitalisations
- 51,200 children with post-measles neurological complications
- 10,700 cases of birth defects due to rubella
- 5400 people paralysed from polio
- and 159,200 deaths.
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Lo said the most likely scenario is one where vaccine coverage continues to drop at a lower rate – but it will still have serious outcomes.
“If we start to see major changes to the childhood vaccination schedule and policy and coverage really drops, you get into a world where you worry about diseases like polio and rubella, but that would likely take well over a decade or more,” he added.
“If that were to happen, you can’t just flip a switch – once these diseases get unleashed, it would take time eliminate them again.”
The wider context
Research consistently shows that vaccines are safe and effective.
A 2024 study in The Lancet revealed that the World Health Assembly’s Expanded Programme on Immunisation has saved approximately 154 million lives over the past 50 years – including 146 million children under 5 years old. This program is likely the single greatest contribution to infant survival over the past 50 years.
A similar study from 2021, also published in The Lancet, found that vaccines against 10 major diseases (including measles, rotavirus, HPV and hepatitis B) prevented 37 million deaths between 2000 and 2019.
Again, the bulk of this number is made up of children under 5. Without vaccination, the mortality rate of this age group would be 45 per cent higher in low- and middle-income countries.
The study’s modelling also found that the total number of deaths prevented could increase to 69 million in the period between 2000 and 2030.
Falling rates
Vaccination rates in children have been dropping since the COVID-19 pandemic, partly due to a rise in vaccine hesitancy.
Last year, Australia’s National Centre for Immunisation Research and Surveillance (NCIRS) reported that vaccination coverage in Australia had dropped for the third consecutive year, particularly in children. The decrease came after 8 years of increasing coverage, before the onset of COVID-19.
Globally, the pandemic fuelled the biggest drop in childhood vaccinations in 30 years, according to data published in 2022 by the World Health Organisation (WHO) and UNICEF.
For example, in 2021, 25 million infants missed out on the lifesaving vaccine for diphtheria, tetanus and pertussis – compared to 19 million missing out in 2019.
WHO and UNICEF cite multiple factors for the decline, including:
- an increased number of children living in areas of conflict where vaccination access is a challenge,
- increased misinformation,
- and service and supply chain disruptions due to COVID-19.
Another study in 2023 focused on measles, showing that millions of children missed MMR vaccinations during the pandemic. Globally, this resulted in an 18 per cent increase in measles cases and a 43% increase in measles-related deaths in 2022, compared to 2021.
A review paper found that the global resurgence of measles in 2024 was due to a “perfect storm” of factors, including “decades of false claims of vaccine adverse events that have included a misleading association with autism, vaccine complacency and hesitancy, and reduced childhood vaccination rates during and after the COVID-19 pandemic”.
The paper urgently calls for public health responses to raise awareness about the seriousness of measles and the vital importance of vaccination programs.
Although vaccination rates in countries like Australia and the US are still high by global standards, the new modelling out of Stanford shows that complacency has serious results, because even small decreases in vaccination coverage can be deadly for thousands.
“With measles, we found that we’re already on the precipice of disaster,” says Kiang.
“It’s worth emphasising that there really shouldn’t be any cases at this point, because these diseases are preventable. Anything above zero is tragic. When you’re talking about potentially thousands or millions, that’s unfathomable.”
This article first appeared in Cosmos Magazine. Read the original here.
