The United States measles outbreak provides a rare insight into the value of vaccination in measles prevention. While there is some doubt on the actual number of deaths being reported (just 2), it is likely the number of notifications and the measles vaccination rates in most states can be trusted.

Local transmission versus imported cases

Most cases in the United States (over 99%) are locally transmitted while those in Australia are mostly imported or related to an imported case. This is an important distinction.

This may change soon if Australia's immunization rates keep falling.

Measles has a high reproduction rate and a small change in community protection levels can have a major impact on transmission, particularly if we are witnessing a deteriorating global picture.

A high community vaccination rate reduces the ability of the virus to spread easily.

Surveillance Data USA (2026) and Vaccination rate

Falling coverage, rising case numbers

The United States coverage rates for kindergarten age children have fallen below the desired target of 95% to 92.4% for the 2025-26 school year. Larger drops are being experienced in some communities around the country.

This fall in coverage is fueling an explosion in case numbers nationally. Local travel, as occurs during the summer months, has likely made the situation worse.

As of October 15, 2026, there have been 4,228 cases of confirmed measles in the United States. Fifty-nine percent (59%) were under 20 years.

Ninety-six percent of the reported cases were either unvaccinated or unknown.

Just 2% of cases had been given the 2-dose course of MMR!

These figures are a concern when compared with the entire year 2025 when there were 2,288 notifications.

John Hopkins provides a real time measles tracker which was last updated in October 2026.

The tracker identifies both imported and local cases, drilling down to individual counties.

According to the tracker, there have been 4,603 cases of measles to week 41 in 2026. The number was 1,568 for the same period in 2025.

In October 2024 it was 267! It is easy to draw conclusions on the cause.

Australia's childhood immunization coverage has also declined over the last 3 years. Rates have fallen below the desired 95% coverage.

More than 121 cases of measles have been notified to Australia's surveillance to October 16, 2026.

What this means for travellers

Measles is a highly infectious disease. Over 90% of non-immune individuals exposed to the disease will become symptomatic. The global risk of measles has increased over the last 2 years.

All travellers, particularly those borne after 1966 should be assessed for their current measles immunisation status. Special attention should be given to the cohort of unvaccinated infants.

At least we can reduce the risk of traveller's importing the disease into Australia.

There were NO cases of measles reported between January 1, 2021, and 18 July 2021 when our international borders were closed!

History of Measles Vaccination in Australia

The live attenuated measles vaccine was first registered in Australia in 1968. It was recommended for children aged 12 to 23 months and given as a single dose vaccination with no booster dose advised. This was not unreasonable given that measles was circulating in the population, and the disease might have served as a booster dose. Any illness would have gone unnoticed at the time.

Measles – mumps was recommended for use in 1982 and later in 1989 was replaced by measles-mumps-rubella (MMR).

As more of the population became immune, transmission reduced and in 1992 a second dose of the MMR vaccine was recommended for all children. The rubella vaccination program for females was replaced by a school-based MMR program for all children aged between 10 and 14 years. All these individuals would have had birth dates in the late 1970's.

It is also important to be aware that prior to the start of measles immunisations, most women would have experienced a bout of the wild disease and hence have a higher antibody response. Children born to these women would have had higher antibody protection during the first year of life, perhaps lasting for up to 8 months. This is not the case for children born to women who have vaccine induced immunity. It is highly unlikely that this immunity affords much protection beyond 3-4 months. This has been investigated in recent years.

This concern might not be an issue if measles transmission was controlled. Australia was declared free of measles in 2014, but a fall in vaccination rates has allowed it back into the country albeit in a limited amount so far. We still have good herd immunity, but this cannot be said for many overseas destinations. This is the reason why travel medicine providers for many years have been giving an early dose of the vaccine to children aged between 6 and 12 months traveling to high-risk destinations. Are we now at a point of saying any destination? I believe this is the case.

It is important that all overseas travellers be aware of the historical aspects of measles vaccination in Australia and why we have been targeting those who have birthdates between 1966 and 1980 and those who have never been vaccinated (children 6 - 12 months).

As public health providers we often fail to sell the message well.

Current Recommendations

• Infants 6–11 months of age should be considered for at least one dose of measles containing vaccine. Most mothers of today have vaccine immunity rather than natural immunity. This provides protection for a shorter period.
• Preschool children ≥12 months of age should have two doses of MMR vaccine separated by at least 28 days.
• School-age children should have two doses of MMR.
• Adults born in or after 1966 should have two doses of measles-containing vaccine.
• If administered at ≥12 months of age, one dose of measles-containing vaccine or MMR is 95% effective in preventing measles disease and two doses are 99% effective. One dose of measles-containing vaccine or MMR is approximately 85% effective if administered at 9 months of age.

The importance of measles vaccine has been discussed previously.

• Another preventable measles death in Texas
• Measles risk in unexpected places: what US and Canadian outbreaks mean for travellers
• Measles cases increasing in Vietnam with shifting age groups
• Large measles outbreak reported in South Sudan
• Measles risk to travellers: bring back memories, not measles