The study also found that participants with concurrent partners were 58% more likely to be the likely source of HIV infection seen in another cohort member, rather than the recipient, and 67% more likely to have apparently passed on their HIV in early infection (between one and six months after infection). It found that men who said they had had condomless sex in the last three months with concurrent partners, rather than just serial partners, were 69% more likely to be in a local transmission pair or cluster that was linked genetically, an indication of HIV transmission between the partners, and the average number of partners they were linked to was 40% greater. A study analysing transmission patterns between gay men in a cohort of patients in San Diego, California has found the strongest scientific evidence so far that concurrency – having ongoing sexual relationships with more than one partner at the same time – is an independent predictor of HIV transmission.