Measles outbreaks in South-East Asia bringing cases to Australia

A surge in measles cases in Southeast Asia has led to the spread of this highly contagious disease to Australia, prompting warnings from health authorities. Vietnam and Thailand are experiencing measles outbreaks, with health professionals expressing concern about vaccination rates for the disease. Dr. Evelyn Wong, acting chief health officer for Victoria, stated in a health alert issued on Saturday that the state's recent four cases were linked to travel in Southeast Asia.

The Victorian health alert noted, "There has been an increase in reports of measles cases in returned travelers across Australia in recent weeks." "Measles is a highly infectious viral illness that can cause rare but serious complications such as pneumonia and encephalitis." New South Wales and Queensland also issued measles health alerts on December 24.

Vietnam's Ministry of Health has reported a staggering 130-fold increase in measles cases in 2024 compared to the previous year. According to state media, there have been 6,725 confirmed cases and 13 deaths. Most deaths occurred in children or older people with underlying health conditions. Thailand has reported 7,507 cases in 2024 compared to just 38 cases in 2023, according to data reported by member states to the World Health Organization.

“Measles is a very serious infection, and it is considered to be the most infectious of the infectious diseases,” said Dr. Sanjaya Senanayake, an associate professor at the Australian National University Medical School. The World Health Organization says one person with measles can infect nine out of ten of their unvaccinated close contacts. The measles virus can remain in the environment for about two hours, and infected people are contagious for more than a week after symptoms appear, which can take 7 to 18 days after exposure to develop. “During outbreaks in areas with low vaccination rates, measles can spread like wildfire,” Dr. Senanayake said.

Measles is a viral infection with symptoms including fever, cough, conjunctivitis (red and sore eyes), runny nose, and a rash. While early symptoms are vague and can be confused with other illnesses, after about four days, a distinctive red blotchy rash appears, starting on 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, particularly in children and immunocompromised adults.

Dr. Senanayake said measles can also cause severe diarrhea, leading to dehydration and death, particularly in developing countries, and can cause a brain infection (encephalitis) in about one in 1,000 cases. He also said there is a rare but fatal brain infection called subacute sclerosing panencephalitis (SSPE) that can occur about seven years after a measles infection. “This infection is completely untreatable, and it’s pretty horrible — you die from it.”

Measles is preventable, and two doses of a vaccine provide 99% protection. Professor Angela Webster, a clinical epidemiologist at the University of Sydney, said that some countries had eliminated or almost eliminated measles before the COVID-19 pandemic. “Due to hesitancy around many routine immunization programs and the disruption caused by the pandemic, it has meant that there are several cohorts of particularly young children who have missed out on their usual childhood vaccinations,” she said, making them more vulnerable to infection.

Dr. Angela Pratt, the WHO representative in Vietnam, said data showed that 70% to 80% of infected children were unvaccinated or under-vaccinated. In addition to pandemic disruptions, she said Vietnam faced vaccine shortages in 2022 and 2023, "resulting in hundreds of thousands of children missing out on measles immunizations." “Young children are most affected, particularly those under five years of age,” she said, adding that infants under 12 months are at the highest risk of serious illness. Globally, 34.6 million children missed measles vaccination in 2023 — 22.2 million missing their first dose and another 12.3 million missing their second.

Dr. Do Tuan Qui from Children’s Hospital 1 in Ho Chi Minh City also raised the issue of under-vaccination in Vietnam, where the measles vaccine has been free for eligible children since 2011. “This is a very worrying problem,” he told VietNamNet Global, a news outlet under Vietnam’s Ministry of Information. The article noted that about 10% of measles patients at the hospital have parents who fear vaccines may cause side effects such as autism — a piece of misinformation that has long been disproven. “Certainly, this misinformation does exist,” Professor Senanayake said. “I have no doubt that the COVID pandemic and the COVID vaccines and vaccine conspiracy theories have just exacerbated the issue exponentially.”

The Bangkok Post reported in September that Thai authorities organized a vaccination campaign after five deaths in its southern provinces, where vaccination rates are typically lower — just 40-50%, compared to the national rate of 80-90%. Dr. Thongchai Keeratihattayakorn, director-general of the Department of Disease Control (DDC), told the Bangkok Post the situation was “very concerning” at the time. He said some parents worried that side effects such as fever could lead to them taking time off work to care for their children, resulting in a loss of income.

Professor Webster added that vaccine coverage is not comprehensive in low- and middle-income countries, and programs are not as well-resourced as in developed countries. Professor Webster noted that both Thailand and Vietnam have large populations and thriving tourism industries. She said that with high numbers of travelers during the Australian summer holidays after Christmas and New Year’s, and the upcoming Lunar New Year (known as Tet in Vietnam) later this month, measles can easily spread. Some Vietnamese media reports say that authorities are considering whether to start vaccinating babies at six months instead of nine months, due to the infections occurring in babies.

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 those who are pregnant or immunocompromised, as it is a live vaccine. People born before 1965 are likely to have gained immunity when the virus was circulating in Australia. Typically, children in Australia receive the vaccine at 12 months and 18 months. But for migrants or those unsure whether they have been vaccinated or do not have vaccination records, health experts say it is best to get vaccinated, particularly if traveling to countries experiencing outbreaks.

Professor Webster said people are more vulnerable due to declining vaccination rates, but they are not aware of it. “Because measles has been so well controlled for many years, they don’t realize how serious measles can be,” she said. Dr. Senanayake said it is worth travelers checking the measles situation in their destination countries and ensuring they are vaccinated. “We’ve seen outbreaks in many other countries around the world, so I don’t think we’re anywhere near the end of measles,” he said. “But from an individual perspective, it’s completely preventable … vaccination is the key.”