PPIB and syphilis: The pilot study showed an increase in HIVST from 3 months compared with 6 months (20% vs. 90%; p < 0.001), as well as significant increases in testing for all four STIs: syphilis (5–48%), gonorrhea (5–43%), chlamydia (1–45%), and hepatitis B testing (14–55%) from baseline to the 6-month follow-up (42).