Early measles vaccination gains urgency amid global outbreak

The global measles outbreak must trigger an urgent debate into whether a vaccine should be recommended earlier to better protect against the highly contagious disease during infancy, a new review states.

The systematic review, led by Murdoch Children's Research Institute (MCRI), found vaccinating children from as early as four months of age for measles warranted serious discussion given that only 30 per cent of babies in low- and middle-income countries were protected by maternal antibodies by four months of age. Concerningly, this is well below the World Health Organization's (WHO) recommendation of a first measles dose between 9-12 months old.

The WHO recommends a two-dose measles vaccine schedule for all children. In many low- and middle-income countries, the first dose is given at nine months and the second dose at 15-18 months. But the exception applies in outbreak situations where vaccination at six months is recommended in addition to the routine two-dose schedule.

Published in The Journal of Infectious Diseases, the review spanned 34 journal articles with data from 8000 babies under nine months of age from low- and middle-income countries. It found maternal measles antibody rates were highest at birth, 81 per cent, before decreasing rapidly to 30 per cent by four months and 18 per cent at seven months.

MCRI Dr. Lien Anh Ha Do said when a first dose had been administered between four to seven months of age it produced a positive immune response and was highly effective in preventing measles.

With 70 per cent of babies having no measles antibodies present by four months old they are being left unprotected before reaching a vaccine-eligible age at 9-12 months.

An early first measles dose could provide sustained protection throughout infancy by closing gaps in immunity. This could be achieved by earlier administration of the first dose or by adding an extra early dose to the routine two-dose schedule." 

Dr. Lien Anh Ha Do, MCRI

But MCRI Professor Kim Mulholland said several barriers existed including the cost-effectiveness of more doses, addressing vaccine hesitancy and uptake and an earlier first dose could also reduce the vaccine's efficacy as the child ages.

"School-aged children are the key transmitters of the virus, so preventing infections during childhood is critical to limiting the disease spread and advancing measles elimination efforts," he said.

"But a trade-off of an earlier first dose is a possible more rapid reduction of measles antibodies in children vaccinated early in infancy. Additionally, adding a third dose will be challenging given that low- and middle-income countries are already struggling to administer a second dose within the current measles vaccination program."

MCRI researcher Darren Ong said to attain herd immunity against measles transmission at least 95 per cent of a population needed to receive both first and second doses.

"Achieving and maintaining this coverage is a significant challenge," he said. The COVID-19 pandemic worsened the situation by interrupting global routine immunisation and catch-up campaigns as well as fuelling vaccine hesitancy.

"A highly contagious airborne virus, measles causes significant impacts especially in young babies who rely on sufficient herd immunity. Poor vaccination coverage has sparked large measles outbreaks in several countries since early 2024."

The current surge in measles infections has been significant, with almost 400,000 measles cases reported globally in 2024 and more than 16,000 during the first two months of 2025.

MCRI Associate Professor Claire von Mollendorf said new and innovative approaches were needed to better control and manage this global health crisis.

"There has been little improvement in global measles control over the past two decades and it's likely the situation will only get drastically worse," she said.

"Rapid diagnostic testing would greatly improve surveillance systems for early detection and monitoring of outbreaks to guide public health responses. New randomised control trials to evaluate the effectiveness of an earlier dosing schedule would also help protect babies who were inadequately protected by maternal antibodies."

New Zealand has recently recommended an additional measles dose be given to children as young as four months before travelling to endemic countries.