The microbicidal gel tenofovir is notably more effective in protecting against HIV among women without vaginal inflammation in comparison with the entire population, reports a study published online this week in Nature Medicine. This finding suggests that tackling genital inflammation (for example with anti-inflammatory drugs) or its underlying causes (such as infections or irritants) may help to increase tenofovir’s protective effect.
Examining HIV infection rates in 889 South African women across a 30-month period, previous research reported that consistent use of tenofovir gel can reduce the risk of HIV transmission during sex by 54%. The gel’s effectiveness, however, was found to vary across different trials, especially among women. The cause of this was suspected to lie not only in social factors - such as inconsistent use - but also in biological differences.
Lyle McKinnon and colleagues looked for inflammatory proteins - which are indicative of inflammation if present in high levels - in the vaginal fluids of 774 women from the previous study. The authors found that in the absence of inflammation, tenofovir reduced the risk of HIV infection by 75% in those who adhered to the study product, a much higher level than previously reported for the overall trial population. Women with vaginal inflammation were found to be at the same risk of contracting HIV as the control group who were given a placebo gel.