Effect of cluster interventions on MSM sexual network and HIV transmission

Objective To examine the effect of cluster interventions on men who have sex with men(MSM) sexual network and human immunodeficiency virus(HIV) transmission in Shenzhen city.Methods Questionnaire survey and blood test for HIV infection were conducted among 379 MSM recruited with respondent-driven sampling in Futian district of Shenzhen city between July and October 2015.Results Among the MSM surveyed, the average size of sexual network was 5.16;the average density of sexual network was 0.33;and the average degree of sexual network connection was 3.71.For the MSM involved with the sexual network of size 6.7, 67.78% participated in cluster interventions and 16.11% were HIV positive;while, for those with the network of size 3.1, 55.36% participated in cluster interventions and 8.93% were HIV positive;there were significant differences in the ratio of participating in cluster intervention and HIV positive rate between the MSM involved with the sexual network of different size(both P<0.05).The MSM, who were involved with the sexual network of 0.5 in density, had significantly higher proportion(74.50% vs.48.60%) of participating in cluster interventions and higher HIV positive rate(18.50% vs.6.70%) compared to the MSM involved with the sexual network of 0.3 in density(both P<0.05).Among the HIV-negative MSM, 60.00% participated in cluster interventions;while, among the HIV-positive MSM, 77.55% participated in cluster interventions, with an odds ratio of 2.30(P<0.05).Conclusion Cluster interventions may expand the size and increase the density of the MSM's sexual network, thus contribute to the spread of HIV among the MSM in Shenzhen city.