A randomized controlled trial in Western Australia identified patients who were at high risk of serious influenza illness and had a mobile phone number on record in their physician's office.
‘Individuals can be influenced by text messages due to various factors including who sends the message, how reliable is the information, and content of the message.’
Among 12,354 eligible patients, half were randomly assigned to an intervention group, which received a vaccination reminder by text message, while the other half (control group) received no text message reminder.
Approximately three months after the messages were sent, 12 percent (n=768) of the intervention group and 9 percent (n=548) of the control group were vaccinated during the study period.
For every 29 messages sent, at a cost of $3.48 (USD), one additional high-risk patient was immunized.
The greatest effect was observed for children under five years of age, whose parents were more than twice as likely to have their child vaccinated if they received a text reminder (RR: 2.43, 95 percent CI: 1.79-3.29). There was no significant effect among pregnant women or Indigenous Australians.
The authors suggest that several factors could influence the effectiveness of text message reminders, including who sends the message, reliability of the contact information, content of the message, and when it is sent.
In light of the substantial burden of influenza on high-risk individuals and health systems, cost-efficient mechanisms to improve vaccine uptake remain an important focus for research and practice.