Discussion
INFLUENZA
Results of this RCT suggest that a parent SMS nudge delivered in the context of tertiary care to children and adolescents with SRMCs increased influenza vaccine receipt. The SMS nudge intervention resulted in a more timely influenza vaccine receipt and during the optimal seasonal influenza period. This is an important finding, given the critical importance of timely influenza vaccination for this group.This study may give policy makers and immunization program managers confidence that targeted nudge interventions can influence uptake. This is further highlighted by the fact that 20% to 25% of the children in this trial had canceled appointments or had their appointments canceled by the hospital due to COVID-19–related restrictions, thus confirming the need for strategies that increase the chances of engaging the parent and creating an opportunity to influence behavior change. During the study, all participants had access to usual care and the clinician nudges, including the opportunity to discuss the influenza vaccine with their child’s specialist, and access to the vaccine through their GP or WCH immunization clinic.An important element of our trial design included the implementation of a waiver of consent, which used a real-world approach to ensure that all children were included in the trial. This is important, as it suggests that our findings are more likely to be representative of this cohort, which will include those who hold antivaccination views and those who are hesitant about vaccination as well as those who have positive health-seeking behaviors. It also suggests that those who do not participate in a research study may, in fact, benefit most from the nudge intervention. This was a key aspect of the trial along with the opportunity to validate influenza vaccine receipt. The wavier of consent for SMS reminders has previously been reported but not with the same effect. An RCT undertaken in the US that used a waiver of consent to implement reminders reported modest gains; however, their usual care included an automated telephone message.Our parent survey in which parents reported being more likely to be prompted through reminders from their child’s specialist as opposed to GPs confirms earlier work in which children are more likely to receive the vaccine if recommended by a specialist.Our survey also showed that parents of unvaccinated children were less likely to have received enough information to decide about their child receiving the influenza vaccine. Given a lack of information has been previously identified as a barrier; this was a potentially crucial outcome. Targeted messaging, including via SMS, could be more effective and may address concerns toward the vaccine, lack of perceived influenza severity, misinformation, and negative social influences that have also been identified.