Statistical methods
During data analyses, we utilised Stata™(Stata Corp LLC, College Station, TX, US) software. For the primary outcome (mean difference in the viral load of HIV-positive children with VLS), we performed ANCOVA using the pre-viral load as a covariate. We compared the mean difference in viral load between the intervention and control groups. Additionally, we used omega-squared to calculate the measure of the effect size. F-tests, with their corresponding p-values, were used as measures of improvement. An interaction test between pre- and post-viral load and age was used to examine the heterogeneity effect. All statistical tests were two-sided; p < 0.05 was considered statistically significant.