Social influence on post-drinking risky sexual behaviours: evidence in France and South Korea

Abstract Background Post-drinking risky sexual behaviours are at the conjunction of the dual risks of sexually transmitted infections and further problematic substance use, necessitating contextual analysis for determinants that promote these behaviours. This study examines the influence of social groups on post-drinking risky sexual behaviours in different cultural samples. Methods A cross-sectional survey was conducted among young adults aged 18-30 in France and in South Korea in 2023-2024 (n = 998). A construct of post-drinking risky sexual behaviours includes 3 types: having sex without condoms, having sex with occasional partners, and having transactional sex. Perceived drinking norms were measured as a proportion. Multivariate logistic regression was conducted after controlling for sociodemographic factors. Results Young adults who reported that their social group had a higher proportion of drinkers were more likely to engage in a wider range of post-drinking risky sexual behaviours (aOR=1.02 [95%CI 1.01-1.03] in France; 1.01 [1.01-1.03] in Korea). Young adults in social groups who had experienced two types of risky sexual behaviours were more likely to engage in risky sexual behaviours after drinking (5.13 [2.21-14.1] in France; 10.65 [5.86-19.8] in Korea), compared to young adults in social groups with no experience. Young adults in social groups who had experienced all three types of risky sexual behaviours had a 10 times higher likelihood of engaging in post-drinking risky sexual behaviours in the French sample (10.12 [3.69-31.4]) and a 16 times higher likelihood in the Korean sample (16.0 [7.31-35.8]). Conclusions Alcohol-related risky sexual behaviours among young adults were found to be significantly associated with their social group’s drinking and risky sexual behaviours, across different cultural settings. More attention should be paid to direct/indirect influence of social groups on health risk behaviours. Key messages • The influence of social groups on alcohol-related risky sexual behaviours is significant regardless of cultural setting. • Peer and social norms-based health promotion is recommended to prevent IST and HIV/AIDS.