Introduction Sex partner change is necessary to maintain STI within a population. However, most people change partners relatively infrequently, and the timing of partner changes relative to incident STI is poorly understood.

Methods 272 participants without STI at enrollment (18–29 years of age; 126 (46%) men/146 (54%) women) from a high STI population completed a 12-week study of daily reports of partner-specific sexual behaviours. None reported commercial sex work. Weekly self-obtained vaginal or urine samples were tested (and treated, if positive) at the end of 12-weeks for C trachomatis (CT), N gonorrhoeae (GC), and T vaginalis (TV) using commercially available NAAT. Survival analysis techniques were used to describe time to first partner change following first NAAT+.

Results 15, 12, and 23 participants acquired an incident CT+, GC+, or TV+ NAAT. Partner change after the first NAAT+ test was seen for 7 (47%), 6 (50%), and 3 (13%) participants with CT+, GC+, or TV+ NAAT, respectively. Median time to partner change after first NAAT+ 7.6 and 4.6 weeks following CT+ or GC+, respectively. Among 231 participants with no incident NAAT+ during 12 weeks of followup, 89 (39%) changed partners.

Conclusion Persons with incident STI have higher rates of partner change than those without incident STI. Rapid partner change is common following a new CT or GC infection, but less common for TV. Interventions focused on short-term partner change could be especially effective approaches to CT and GC control efforts.

Disclosure of interest statement This research was funded by the National Institute of Child Health and Human Development. The authors have no relevant conflict of interest to disclose.