Comparison between the characteristics of the patients included into small (2–3 patients/cluster) or large (>4 patients/clusters) clustered events.

Note: the total of patients for each variable does not always equal the total sample due to some missing values.(1)Urethritis, rectitis, genital herpes infection, vulvovaginal candidosis, condyloma and/or syphilis.(2)In the last 6 months preceding PHI diagnosis.