So here’s an interesting paper. The authors looked at self-reported Sexually Transmitted Infections (STIs) and self-reported sexual history over the past year in a cross-sectional study in St. Petersburg, Russia. This design might raise a red flag or three regarding the reliability of the data, but unless you can tell me how misreporting is likely to be correlated with (what I think is) the key finding, that doesn’t undermine their work all that much.
What they report is that short relationship gaps (1-90 days) put people at higher risk than overlapping (concurrent) relationships. The authors suggest:
The present study’s findings may seem counterintuitive, but we might explain them with a scenario in which people with short partnership gaps have more frequent sexual intercourse with their STI-infected partner than do individuals with overlapping relationships, provided that both groups have similar rates of condom use, which was the case in our study
Specifically, they argue that concurrent partnerships require you to be having sex with multiple people at once, and thus you can’t give each partner as much attention as you can in a serially monogamous relationship.
I thought that this paper was interesting because it helped me to remember that while concurrency is dangerous for STIs, closely packed serial relationships can be just as bad, if the gap between relationships is less than the incubation window period plus the period of high infectiousness around breakout. This is especially true if, as seems reasonable (although the interwebs/PubMed is not helping me with longitudinal evidence of sexual behaviour within relationships – sounds like a paper to me) people have more frequent sex at the beginning of relationships.
An Aside: Interestingly, another paper from the same study noted that your partners’ concurrency status is associated with your disease status, but given that, yours doesn’t actually matter. As ever, who you’re involved with is more important than how many you’re involved with…
Paper: Zhan W, Krasnoselskikh TV, Golovanov et al. Gap between Consecutive Sexual Partnerships and Sexually Transmitted Infections Among STI Clinic Patients in St Petersburg, Russia. AIDS and Behavior, 2011; epub ahead of print. DOI: 10.1007/s10461-011-9932-z. Link (gated).