Protective factors for adolescent sexual risk behaviours and experiences linked to HIV infection in South Africa: a three-wave longitudinal analysis of caregiving, education, food security, and social protection

BACKGROUND: Structural interventions are endorsed to enhance biomedical and behavioural HIV prevention programmes for adolescents. Aiming to inform future interventions, we evaluated longitudinal associations between six protective factors that link closely to existing structural HIV prevention interventions, and five sexual risk behaviours for HIV transmission in a cohort of adolescents in South Africa. METHODS: We used three rounds of data between 2014–2018 on 1046 adolescents living with HIV and 473 age-matched community peers in South Africa’s Eastern Cape (Observations = 4402). We estimated sex-specific associations between six time-varying protective factors − number of social grants, education enrolment, days with enough food, caregiver supervision, positive caregiving, and adolescent-caregiver communication; and five HIV risk behaviours − multiple sexual partners, transactional sex, age-disparate sex, condomless sex, and sex on substances. HIV risk behaviours were analysed separately in multivariable random effects within-between logistic regression models that accounted for correlation of repeated observations on the same individual. We calculated prevalence ratios (PR), contrasting adjusted probabilities of HIV risk behaviours at ‘No’ and ‘Yes’ for education enrolment, and average and maximum values for the other five protective factors. RESULTS: The sample mean age was 15.29 (SD: 3.23) years and 58% were girls. Among girls, within-individuals, increases from mean to maximum scores in positive caregiving were associated with lower probability of transactional sex (PR = 0.79; 95%CI = 0.67–0.91); in caregiver supervision were associated with lower probability of transactional sex (PR = 0.75; 95%CI = 0.66–0.84), and age-disparate sex (PR = 0.84; 95%CI = 0.73–0.95); in adolescent-caregiver communication were associated with higher probability of transactional sex (PR = 1.70; 95%CI = 1.08–2.32); and in days with enough food at home were associated with lower probability of multiple sexual partners (PR = 0.89; 95%CI = 0.81–0.97), and transactional sex (PR = 0.82; 95%CI = 0.72–0.92). Change from non-enrolment in education to enrolment was associated with lower probability of age-disparate sex (PR = 0.49; 95%CI = 0.26–0.73). Between-individuals, relative to mean caregiver supervision scores, maximum scores were associated with lower probability of multiple sexual partners (PR = 0.59; 95%CI = 0.46–0.72), condomless sex (PR = 0.80; 95%CI = 0.69–0.91), and sex on substances (PR = 0.42; 95%CI = 0.26–0.59); and relative to non-enrolment, education enrolment was associated with lower probability of condomless sex (PR = 0.59; 95%CI = 0.39–0.78). Among boys, within-individuals, increases from mean to maximum scores in positive caregiving were associated with lower probability of transactional sex (PR = 0.77; 95%CI = 0.59–0.96), and higher probability of condomless sex (PR = 1.26; 95%CI = 1.08–1.43); in caregiver supervision were associated with lower probability of multiple sexual partners (PR = 0.73; 95%CI = 0.64–0.82), transactional sex (PR = 0.63; 95%CI = 0.50–0.76), age-disparate sex (PR = 0.67; 95%CI = 0.49–0.85), and sex on substances (PR = 0.61; 95%CI = 0.45–0.78), and in days with enough food at home were associated with lower probability of transactional sex (PR = 0.91; 95%CI = 0.84–0.98). CONCLUSION: Effective structural interventions to improve food security and education enrolment among adolescent girls, and positive and supervisory caregiving among adolescent girls and boys are likely to translate into crucial reductions in sexual risk behaviours linked to HIV transmission in this population. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12889-023-16373-5.