Effects of new pictorial cigarette pack warnings on Vietnamese smokers’ perceptions and smoking behaviors: a single-factor, between-subjects experimental study

This study aimed to assess the effects of different cigarette package pictorial health warnings (PHW) configurations that Vietnam might consider in the future. A 5-arm randomized experiment was conducted with 1,010 adult smokers in Vietnam in 2024. We measured four sets of outcomes: (1) emotional and cognitive responses, (2) attitudes and beliefs about smoking-related harms, and (3) behavioral intentions measured immediately after viewing PHWs; and (4) recall and behavioral outcomes at two-week follow-up. Group 2 (new PHWs, covering 85%) had significantly higher negative emotional responses than group 4 (new PHWs + Quitline + Plain packaging, covering 85%). For ‘smoking causes oral cancer’ and ‘smoking causes bleeding in the brain and stroke’, the mean belief scores of group 2 (new PHWs, covering 85%) were significantly higher than those of the control group. At two-week follow-up, participants in group 3 (new PHWs + Quitline, covering 85%) and group 4 (new PHWs + Quitline + plain packaging, covering 85%) were more likely to recall the quitline number compared to the control group. Additionally, participants in group 4 (new PHWs + Quitline + plain packaging, covering 85%) had higher odds of forgoing a cigarette at two-week follow-up compared to the control group. No significant impact of groups on quit intention or cessation behaviors was observed. Our study supports refreshing PHWs, showing that new PHWs with quitline enhanced awareness of quitline services. Plain packaging with new PHWs increased the likelihood of forgoing cigarettes, a precursor to cessation attempts. Trial registered at ClinicalTrials.gov (NCT06818786, 24/08/2024).