Firstly, low incidence is expected in a largely heterosexual population, with higher incidence rates (range 21–46 per 100 person-years) reported in previous studies among MSM.[26, 27] Secondly, our participants had stable HIV disease since two thirds of the men were already on ART at enrolment with a median CD4+ count of 445 cells/μL and thus were likely able to mount a sufficient immune response to clear an infection which occurred soon after the first negative test. Here, CD4 is linked to infection.