Vaginal swab ‘detects HIV exposure in an hour’

Self-administered daily procedure could help identify those at risk

SELF-administered daily vaginal swabs can detect HIV exposure within an hour, a new study by the HIV Vaccine Trials Network (HVTN) has found.

Researchers evaluated the use of the swabs to detect HIV in conjunction with a cellphone survey. They enrolled 50 sexually active HIVnegative women in Soweto, aged 18 to 25, and asked them to self-administer daily vaginal swabs in conjunction with a daily cellphone-based survey on sexual behaviour over a period of 90 days.

“As part of the study, participants were also provided with HIV testing and counselling, STI testing and treatment, and gynaecological exams and Pap smear. Clinicians collected swabs at regular clinic visits over the course of the study, analysing them for biomarkers of vaginal secretions, semen and HIV,” the network said.

The HVTN said the study demonstrated that vaginal self-swabbing and biomarker testing can be useful to validate behavioural data collection methods, such as cellphone-based questionnaires.

“Improving the sensitivity of HIV RNA detection in the vagina is essential to using this approach to consistently detect HIV exposure. None of the participants acquired HIV during the study.

“To assess vaginal HIV exposure, all vaginal swabs that were linked to phone reports of sex without condoms were tested for HIV genetic material, or RNA. Analysis of the swabs found that only one of 69 samples collected between zero to one hour after sex had detectable HIV RNA.

“None of the 247 samples collected from one to four hours after sex had detectable HIV. None of the 185 samples with evidence of semen collected from four to 24 hours after sex had detectable HIV,” the network said in a statement.

Ways to measure exposure to HIV could be important in helping identify those at the greatest risk of acquiring the virus, improving the design of future HIV-prevention efficacy trials and public health interventions.

“The detection of HIV in one sample demonstrates the possibility of detecting the virus through selfcollected swabs. However, compared to current HIV transmission rates in the area, HIV exposure detection in the study was lower than expected.

Lead author of the study Maria Lemos said: “In the future, we plan to extend the work we have done to measure HIV exposures and condomless sex in women to also include men who have sex with men.

“We plan an additional study to establish similarities and differences in daily behavioural reporting by men who have sex with men using mobile apps, and to assess biomarkers of condomless sex and HIV exposures in the rectum like we did in the vagina,” she added.

We plan a study of men to assess biomarkers of condomless sex… Maria Lemos Lead author of research