Intervention and Control Groups
Participants in the intervention group watched through the messaging application 1 of the online health promotion videos (lasting approximately 3 minutes) tailored to their SOC regarding SIV uptake once every 2 weeks for 4 sessions at week 0, 2, 4, and 6. The health communication messages in these videos followed the strategies to facilitate progression in SOC recommended by the TTM.At the beginning of each session, the intervention system assessed participants’ SOC by asking them 2 questions: whether they intended to obtain SIV in the next 6 months, and whether they planned to do so in the next month. Stages of change were as follows: precontemplation stage, defined as without intention to obtain SIV in the next 6 months; contemplation stage, defined as intention to obtain SIV in the next 6 months but without plans to do so in the next month; and preparation stage, defined as intention to obtain SIV in the next month. The same measurements and definitions of SOC were commonly used in studies of vaccination behaviors.