A surge in measles in South-East Asia is bringing cases of the highly infectious disease to Australian shores, prompting warnings from health authorities.
Vietnam and Thailand are experiencing measles outbreaks, with health professionals concerned about vaccination rates against the disease.
In a health alert issued in Victoria on Saturday, acting chief health officer Dr Evelyn Wong said four recent cases in the state had been linked to travel from South-East Asia.
"There has been an increase in notified cases of measles in returned travellers across Australia in recent weeks," the Victorian health alert said.
"Measles is a highly infectious viral illness that can lead to uncommon but serious complications, such as pneumonia and brain inflammation (encephalitis)."
New South Wales and Queensland also issued health alerts for measles on December 24.
In Vietnam, the health ministry reported a whopping 130-fold increase in measles cases in 2024 compared to the previous year.
There were 6,725 confirmed cases and 13 fatalities, according to state media reports.
Most of the fatalities were in children or elderly people with underlying health conditions.
According to data reported to the World Health Organization by member states, Thailand had 7,507 cases in 2024, compared to just 38 in 2023.
What are measles symptoms?
"Measles is a very nasty infection," said Dr Sanjaya Senanayake, an associate professor at the ANU School of Medicine.
"It is thought to be our most infectious communicable disease."
The World Health Organization says one measles patient can infect nine out of 10 of their unvaccinated close contacts.
It lingers in the environment for around two hours, and a person with measles remains contagious for more than a week, and symptoms may not appear until seven to 18 days after exposure.
"During outbreaks in low vaccination areas, it spreads like wildfire," Dr Senanayake said.
It's a viral infection with symptoms including:
- fever
- cough
- conjunctivitis (red and sore eyes)
- runny nose
- rash
While the early symptoms are vague and could be mistaken for other illnesses, in about four days the tell-tale red spotty rash will emerge, starting at the head and neck before spreading to the rest of the body.
While many people will feel unwell and then recover, measles can lead to complications, such as ear infections and pneumonia, especially in children and immunocompromised adults.
Dr Senanayake said it can also cause severe diarrhoea that can lead to dehydration and death, particularly in the developing world, and also brain infection (encephalitis) in about one in 1,000 cases.
He said there's also a rare but fatal type of brain infection called SSPE, which can occur about seven years after a measles infection.
"And that's completely untreatable and a horrible infection — you just die from that."
What's behind the outbreaks?
Measles is preventable, with two doses of the vaccine providing 99 per cent protection.
Angela Webster, a professor of clinical epidemiology at the University of Sydney, said several countries had eliminated or almost eliminated measles before the COVID-19 pandemic came along.
"Because of the suspicion of many regular immunisation programs and because of the disruption caused by the pandemic, it meant there's a couple of [cohorts] of particularly younger children who didn't receive the usual vaccinations of childhood," she said.
That made them much more vulnerable to infection.
Dr Angela Pratt, the WHO representative for Vietnam, said data suggested 70 to 80 per cent of children with the infection were unvaccinated or under-vaccinated.
Apart from pandemic disruptions, she said Vietnam faced vaccine stock-outs in 2022-2023, "resulting in hundreds of thousands of children missing out on being immunised against measles".
"Young children have been the most affected group, particularly children under five years of age," she said, adding infants under 12 months were at the highest risk of severe illness.
Globally, 34.6 million children missed a measles vaccine dose in 2023 — 22.2 million missed their first dose and an additional 12.3 million missed their second dose, according to the WHO.
The lack of vaccination in Vietnam, where the measles vaccine has been free for eligible children since 2011, was also raised by Du Tuan Quy, from Ho Chi Minh City Children's Hospital 1.
"This is a very concerning issue," he told VietNamNet Global, a news outlet aligned with the country's Ministry of Information.
The article suggested around 10 per cent of the parents of measles patients at the hospital feared the vaccine could have side effects like autism — a long-debunked piece of misinformation.
"Certainly that misinformation that is out there," Professor Senanayake said.
"There's no doubt in my mind that what happened with COVID and COVID vaccines and vaccine conspiracies just has escalated exponentially that issue."
The Bangkok Post reported in September that Thai authorities organised a vaccination drive after five fatalities in its southern provinces, where vaccine rates were typically lower — just 40-50 per cent, compared to 80-90 per cent nationally.
Dr Thongchai Keeratihattayakorn, director-general of the Department of Disease Control (DDC), told the Bangkok Post the situation at the time was "very worrisome".
He said some parents were concerned side effects like fever could lead to them taking time off work to care for their child and a loss of income as a result.
In lower-and middle-income countries, vaccine coverage is not as comprehensive and programs are not as well-resourced, Professor Webster added.
Professor Webster pointed out both Thailand and Vietnam have high populations and thriving tourist industries.
She said that measles can spread easily at this time of high travel, after Christmas and New Year, with summer holidays in Australia, and Lunar New Year (known as Tet in Vietnam) approaching later this month.
Some media reports from Vietnam suggested authorities were mulling whether to begin vaccination from six months instead of nine months, due to infections in babies.
Health departments in Thailand and Vietnam were contacted for comment.
Push for vaccination
In Australia, the Measles, Mumps and Rubella (MMR) vaccine is free and available to everyone born after 1965, regardless of Medicare eligibility.
The exceptions are for those who are pregnant or with low immune systems, as it is a live vaccine.
Those born before 1965 likely have immunity from when the virus was circulating in Australia.
Typically children in Australia will receive the vaccine at 12 and then 18 months.
But for migrants or those who are unsure if they've had the vaccine, or do not have documentation for it, health experts say it's a good idea to get vaccinated — especially if travelling to a country where outbreaks are occurring.
Professor Webster said because vaccination rates have slipped, people were more vulnerable but didn't realise it.
"They've been protected from understanding how serious measles is because it's been so well controlled for so many years," she said.
Dr Senanayake said it was worth travellers checking the measles situation in destination countries and making sure they were vaccinated.
"We've seen outbreaks in a number of other countries around the world, so I don't think we're anywhere close to seeing the end of measles yet," he said.
"But from an individual point of view, it's completely preventable … vaccination is key."
