On October 1, 2026 (October 2 in Australia), researchers from Monash University and Bayside Health's Melbourne Sexual Health Centre published new findings in The Lancet Obstetrics, Gynaecology & Women's Health on why bacterial vaginosis (BV) keeps coming back, even when couples are treated together. The same group made headlines in March 2025 with a New England Journal of Medicine trial showing that BV can be sexually transmitted by male partners, and that treating those partners alongside women cut recurrence by more than 60%. That work went on to win this year's Australian Infectious Diseases Research Centre Eureka Prize for Infectious Diseases Research, according to Monash's release via News-Medical. The new paper looks at the roughly 20% of women who were not cured even with partner treatment.

Why It Matters

BV is one of the largest recurring consumer problems in intimate health, and many of the products sold around it assume the problem is "balance": pH washes, boric acid suppositories, probiotics and microbiome test kits. This research sharpens a different picture. For a meaningful share of women, recurrence is an incomplete-clearance problem that can be detected the day after treatment. For others, it is a transmission problem that requires the partner to be treated. Both findings favor diagnostics and clinician-led care over generic OTC "rebalancing." For the vaginal-microbiome testing companies we have tracked, including Evvy, Juno Bio and Good Clean Love's clinical line, a measurable early marker of persistence is a clear clinical use case: test right after treatment and escalate if the microbiome hasn't shifted. For telehealth platforms, the partner-treatment model that Melbourne has been building since 2025 means prescribing for two people, which current women's-health telehealth flows are not designed to do. The IUD signal is preliminary, but contraception providers should watch it.

The study followed 188 heterosexual couples. Women took a one-week course of oral antibiotics, and their male partners received both oral and topical antimicrobials. The researchers identified two separate routes back to BV: persistence, where BV-associated bacteria survive the week-long course, and reinfection from a partner. The day after finishing treatment, about two-thirds of women had returned to an "optimal" Lactobacillus-dominated vaginal microbiome. The other third had microbiomes suggesting they "may not have cleared their BV" before the couple resumed sex, and they were nearly three times as likely to have BV again within four weeks, lead author Dr Lenka Vodstrcil told The Guardian. About 30% of the women used an intrauterine device, which the paper says "could enhance the persistence" of BV after treatment in some women, though more research is needed.

The team now plans to trial longer treatment courses and combinations of antibiotics aimed at the persistent group. "Our aim is to stop women from having two, three, four courses of antibiotics throughout the year, which was happening previously," Vodstrcil said. Senior author Professor Catriona Bradshaw described the strategy as using partner treatment to block reinfection and "more intensive strategies that target persistence of BV-bacteria" to raise cure rates. The authors caution that participants were representative of urban Australia, and the results may not generalise to low- and middle-income settings or other populations with a high BV burden.

BV affects about one in four women worldwide. It can cause itching, burning and discomfort, raises susceptibility to other infections, and is linked to complications in pregnancy and childbirth.

Sources

Update — 2026-10-03

Initial entry — story first created.