New Australian research suggests that reminding parents about their child’s vaccinations by text increases on-time vaccination by 6%.
Vaccination rates among Australian children have been steadily declining in recent years. To combat this, a team of local researchers has turned to the humble text message.
The new research, published in The Lancet Regional Health – Western Pacific, explored the effectiveness of a variety of different SMS reminders sent to parents on improving rates of timely vaccination in their children.
“We found evidence that SMS reminders are effective for achieving modest but important gains in on-time vaccination for young children,” said Professor Tom Snelling, head of Infectious Disease Implementation at the Wesfarmers Centre of Vaccines and Infectious Diseases and senior author on the new research
“There was no definitive evidence that any specific SMS framing or timing combination was likely to be better than all others, but there was evidence that persuasive reminders may be more effective than neutral reminders,”.
Almost 10,000 parents from 20 participating clinics across Australia were randomised as part of the trial, with roughly 11,500 children scheduled to receive at least one vaccine during the study period. All states and territories had at least one clinic participate in the trial, apart from South Australia, with four clinics located in rural local government areas and two clinics located in the most socioeconomically disadvantaged quintile of local government areas.
Participating parents were randomised to receive no SMS or one of four differently framed reminders: a neutral reminder that only stated that a vaccination was due; a “positively-framed” reminder that highlighted the personal benefits of vaccines; a “risk-based” reminder that warned parents of the potential dangers of putting off vaccination and a “social benefits” reminder that explained the benefits of vaccination to the wider community as well as to the child.
Parents randomised to the SMS arm could receive the text message “nudges” at one of three time points: 14 days before the vaccination was due, the day the vaccination was due or seven days after the vaccine was due.
Therefore, parents belonged to one of 13 different trial arms. Of the 9993 parents included in the trial, 637 were randomised to the control (no SMS) arm. The remaining parents were distributed across the other 12 groups, with the final size of these groups ranging from 380 to 1110.
“A unique aspect of this study was that every single element was designed to be digitally automated, from sending the SMS reminders right through to the data analysis – making this a simple, effective and low-cost strategy that could be easily implemented at GP clinics,” said Professor Snelling.
The primary outcome of interest for the researchers was on-time vaccination, defined as a child receiving the scheduled vaccination at the study site between 14 days prior to and 28 days after the vaccination’s due date.
When the 12 SMS groups were pooled for an overall comparison against the no SMS reminder group, the children of parents who received a text reminder were 29% more likely to receive their vaccine on time. The real-world effect of this is that the SMS reminders saw an estimated 6% increase in the proportion of children vaccinated on time.
The effect of the different reminder messages being sent at one of the three potential timepoints on the likelihood of timely vaccination ranged from 2% (not significantly different to the no SMS group) to 53%. The “alternatively framed” text messages were similarly effective to the no SMS group when they were considered individually, but the neutral tone reminder was less effective at improving timely vaccine rates compared to the more persuasive framings.
“The SMS reminders came directly from the GP clinics, and I believe this played an important role in the successful outcome as parents respond positively to a trusted, credible source of information,” Professor Snelling explained.
“In Australia, general practitioners are primarily responsible for delivering routine childhood vaccines and are also widely trusted as a source for vaccine information; it is unclear whether reminders sent anonymously or from other sources (e.g. government) would have had similar acceptance by parents or response rates,” Professor Snelling and his co-authors elaborated in the manuscript.
“Only a single request to opt out was received from over 20,000 unsolicited SMS reminders issued, suggesting that even if not always acted upon, the reminders were tolerated well by parents.”
Related
While the researchers were understandably pleased with their findings, there were several important limitations that need to be considered when discussing the results.
“A main limitation of the trial is that we were unable to ascertain vaccine receipt outside of the source clinics,” the researchers wrote.
“Because Australian parents are free to choose the vaccine provider for their child, it is possible that the reminders diverted vaccine delivery toward the source clinics from elsewhere, with little or no overall increase in on-time vaccination.
“[Also,] it is possible that SMS reminders brought forward vaccine doses that would have eventually occurred regardless, so we cannot claim an effect of reminders on schedule completion.”
Another important consideration to note is that the researchers did not specifically target reminders to Australian First Nations or other culturally or linguistically diverse families – where vaccination rates in young children are typically lower compared to non-Indigenous families where English is the first language – nor did they capture data on ethnicity.
“While our SMS wording was co-developed with a community reference group and validated via a parent survey, these were primarily English-speaking parents and reminders may need to be co-developed and evaluated in diverse communities to ensure broad appropriateness and effectiveness,” the researchers noted.
Despite these limitations, the researchers have big plans moving forward.
“These results also suggest potential for using SMS reminders to improve health behaviours for other GP-led public health screening programs, like reminding people to undergo blood pressure checks or cancer screening,” said Professor Snelling.
“Australia’s National Immunisation Program has been expertly designed to ensure children receive maximum protection at the exact time they need it most, so delaying scheduled immunisations by weeks or months can leave a child at serious risk of life-threatening diseases,” said Mrs Catherine Hughes, honorary community co-researcher at the Wesfarmers Centre and Executive Director of the Immunisation Foundation of Australia.
“This is more important than ever in the current global situation, where vaccine hesitancy is growing and many countries around the world are losing their measles-free status – Australian toddlers receive full protection against measles at their 18-month immunisations so it is essential they receive it on time.
“In the future, I would like to see this strategy used to ‘nudge’ parents into accessing the flu vaccine, not just for their children but for themselves as well – this would go a long way in tackling the dangerously low uptake rates we are currently seeing.”
The Lancet Regional Health – Western Pacific, 11 February 2026
