Measles has been rising globally in recent years. There were an estimated 10.3 million cases worldwide in 2023, a 20% increase from 2022.

Outbreaks are being reported all over the world including in the United States, Europe and the Western Pacific region (which includes Australia). For example, Vietnam has reportedly seen thousands of cases in 2024 and 2025.

In Australia, 77 cases of measles have been recorded in the first five months of 2025, compared with 57 cases in all of 2024.

Measles cases in Australia are almost all related to international travel. They occur in travellers returning from overseas, or are contracted locally after mixing with an infected traveller or their contacts.

Measles most commonly affects children and is preventable with vaccination, given in Australia in two doses at 12 and 18 months old. But in light of current outbreaks globally, is there a case for reviewing the timing of measles vaccinations?

Some measles basics

Measles is caused by a virus belonging to the genus Morbillivirus. Symptoms include a fever, cough, runny nose and a rash. While it presents as a mild illness in most cases, measles can lead to severe disease requiring hospitalisation, and even death. Large outbreaks can overwhelm health systems.

Measles can have serious health consequences, such as in the brain and the immune system, years after the infection.

Measles spreads from person to person via small respiratory droplets that can remain suspended in the air for two hours. It’s highly contagious – one person with measles can spread the infection to 12–18 people who aren’t immune.

Because measles is so infectious, the World Health Organization (WHO) recommends two-dose vaccination coverage above 95% to stop the spread and achieve “herd immunity”.

Low and declining vaccine coverage, especially since the COVID pandemic, is driving global outbreaks.

When are children vaccinated against measles?

Newborn babies are generally protected against measles thanks to maternal antibodies. Maternal antibodies get passed from the mother to the baby via the placenta and in breast milk, and provide protection against infections including measles.

The WHO advises everyone should receive two doses of measles vaccination. In places where there’s a lot of measles circulating, children are generally recommended to have the first dose at around nine months old. This is because it’s expected maternal antibodies would have declined significantly in most infants by that age, leaving them vulnerable to infection.

If maternal measles antibodies are still present, the vaccine is less likely to produce an immune response.

Research has also shown a measles vaccine given at less than 8.5 months of age can result in an antibody response which declines more quickly. This might be due to interference with maternal antibodies, but researchers are still trying to understand the reasons for this.

A second dose of the vaccine is usually given 6–9 months later. A second dose is important because about 10–15% of children don’t develop antibodies after the first vaccine.

In settings where measles transmission is under better control, a first dose is recommended at 12 months of age. Vaccination at 12 months compared with nine months is considered to generate a stronger, longer-lasting immune response.

In Australia, children are routinely given the measles-mumps- rubella (MMR) vaccine at 12 months and the measles-mumps-rubella-varicella (MMRV, with “varicella” being chickenpox) vaccine at 18 months.

Babies at higher risk of catching the disease can also be given an additional early dose. In Australia, this is recommended for infants as young as six months when there’s an outbreak or if they’re travelling overseas to a high-risk setting.

A new study looking at measles antibodies in babies

A recent review looked at measles antibody data from babies under nine months old living in low- and middle-income countries. The review combined the results from 20 studies, including more than 8,000 babies. The researchers found that while 81% of newborns had maternal antibodies to measles, only 30% of babies aged four months had maternal antibodies.

This study suggests maternal antibodies to measles decline much earlier than previously thought. It raises the question of whether the first dose of measles vaccine is given too late to maximise infants’ protection, especially when there’s a lot of measles around.

Should we bring the measles vaccine forward in Australia?

All of the data in this study comes from low- and middle-income countries, and might not reflect the situation in Australia where we have much higher vaccine coverage for measles, and very few cases.

Australia’s coverage for two doses of the MMR vaccine at age two is above 92%.

Although this is lower than the optimal 95%, the overall risk of measles surging in Australia is relatively low.

Nonetheless, there may be a case for broadening the age at which an early extra dose of the measles vaccine can be given to children at higher risk. In New Zealand, infants as young as four months can receive a measles vaccine before travelling to an endemic country.

But the current routine immunisation schedule in Australia is unlikely to change.

Adding an extra dose to the schedule would be costly and logistically difficult. Lowering the age for the first dose may have some advantages in certain settings, and doesn’t pose any safety concerns, but further evidence would be required to support this change. In particular, research is needed to ensure it wouldn’t negatively affect the longer-term protection that vaccination offers from measles.

Making sure you’re protected

In the meantime, ensuring high levels of measles vaccine coverage with two doses is a global priority.

People born after 1966 are recommended to have two doses of measles vaccine. This is because those born before the mid-1960s likely caught measles as children (when the vaccine was not yet available) and would therefore have natural immunity.

If you’re unsure about your vaccination status, you can check this through the Australian Immunisation Register. If you don’t have a documented record, ask your doctor for advice.

Catch-up vaccination is available under the National Immunisation Program.

Meru Sheel, Associate Professor, Infectious Diseases, Immunisation and Emergencies (IDIE) Group, Sydney School of Public Health, University of Sydney and Anita Heywood, Associate Professor, School of Population Health, UNSW Sydney

This article is republished from The Conversation under a Creative Commons license. Read the original article.