The protective effect of condoms and nonoxynol-9 against HIV infection
Wittkowski, K.M.; Susser, E.; Dietz, K.
American Journal of Public Health 88(4): 590-596
1998
ISSN/ISBN: 0090-0036 PMID: 9551000 DOI: 10.2105/ajph.88.4.590Document Number: 274444
Whether or not spermicides can reduce the risk of HIV transmission remains an important question for the control of heterosexual HIV transmission. The authors provide estimates from a reanalysis of one of the few observational studies on the efficacy of condoms and spermicides, used separately and together, per vaginal contact. Reported use of barrier methods among 27 432 contacts was as follows: condoms plus nonoxynol-9 (N-9), 39%; condoms alone, 25%; N-9 alone, 24%; and unprotected, 11%. Under all 3 models, the results indicate a strong protective effect for spermicidal suppositories. The Pearl index indicated that spermicide alone is apparently efficacious, but the efficacy per contact cannot be quantified with this approach. Maximum likelihood estimates for the efficacy of N-9 alone and condoms (with or without N-9) were 100% (95% CI = 43%, 100%) and 92% (95% CI = 79%, 100%), respectively.