Parental Reminder Strategies and the Cost Implication for Improved Immunisation Outcomes: A Systematic Review and Meta-Analysis

"Mobile technology has now opened up the space and offers an opportunity for improved communication between health practitioners and clients and is now being explored further for improved immunisation indicators..."

In both developed and developing countries, several factors impede the active involvement of parents in immunisation services, such as negligence and forgetfulness. To address these problems, studies on parental reminder strategies have been conducted. This review systematically reviews different parental reminder interventions and their cost implications for improved immunisation uptake.

The researchers used the 2020 version of Preferred Reporting Items for Systematic reviews and Meta-Analysis (PRISMA), seaching 5 online databases from June 29 to July 7 2022. Twenty-four articles published between 2015 and 2022 met the inclusion criteria. A total of 54,224 parents were recruited as participants in all the studies, 5 of which were conducted in high-income countries and 19 of which were conducted in low- or middle-income countries. Four of the studies were quasi-experimental, while the remaining 20 were randomised control trials (RCTs). Of the 20 RCTs, 3 were cluster randomised trials.

Of the 24 studies, 19 provided sufficient information and were therefore included for meta-analysis. The 19 studies assess 5 different parental reminder/recall strategies - short message service (SMS) reminder and incentive, reminder SMS, voice call, SMS-delivered health education, and voice call with SMS reminder - on 2 immunisation outcomes: coverage and timeliness of immunisation among children.

With regard to coverage, findings reveal that all types of intervention were statistically significant for improving immunisation coverage except for SMS health education. For example, results indicate that a heterogeneous and low-quality certainty of evidence on parental voice calls (odds ratio (OR) 4.752, 95% confidence interval (CI) 1.846-12.231, p = 0.001) exists in improving immunisation coverage. Put another way, voice-call-based intervention was about 5 times more likely to improve immunisation coverage compared to the control group with standard practice.

Regarding immunisation timeliness, the review found that a high-quality certainty of evidence on SMS-delivered health education messages (OR 2.711 95% CI 1.387-5.299, p = 0.004) had a significant effect on timely immunisation uptake. The effect of incentives on timely immunisation uptake was also found to be statistically significant, with the pooled effect of OR 2.151, 95% CI 1.613, 2.867, p-value = 0.001. In other words, incentives can improve timely immunisation uptake by 2.1 times compared to standard routine care.

The average cost of SMS-delivered parental reminder interventions for improved immunisation outcomes was $US0.50. Evidence indicates that for every $US1 spent to vaccinate a child, about $US79 is saved.

"Policymakers can use the results of this review and apply them to their context by designing appropriate interventions such as health information using local languages for hard-to-reach populations to create more awareness and thereby reduce vaccine hesitancy. This can also help bridge the wide health inequality gap among the rural-urban population, thereby creating inclusion and increasing the use of vaccines."

The researchers recommend that future studies consider factors such as the appropriate timing of mHealth messaging, use of local languages to send messages, and how to reach male partners in addition to women, especially in low- and middle-income countries (LMICs). Population-specific modules could be developed that can be used for mHealth educational interventions for improved vaccine use.

The review concludes that mobile technology is a promising, cost-effective strategy for improved immunisation outcomes.