The Visby Medical Women’s Sexual Health Test ? a single-use PCR platform that combines sample preparation, nucleic acid amplification, and detection into an integrated device ? offers an over-the-counter solution for the detection of DNA from pathogens such as Chlamydia trachomatis (CT), Neisseria gonorrhoeae (NG), and Trichomonas vaginalis (TV).

“Chlamydia, gonorrhoea, and trichomoniasis are the three most common sexually transmitted infections (STIs) that are easily treatable if diagnosed,” said Dr Shradha Prabhulkar from Visby Medical, San Jose, California, US, at IDWeek 2024. “If left untreated, however, these can lead to severe health consequences, including fertility.”

Clinical trial

A clinical study was conducted in simulated ‘at-home’ settings across 13 geographically diverse sites in the US. A total of 2,203 female participants aged ≥14 years were instructed to follow instructions for self-collecting a vaginal swab, with no prior training or help from the study staff. The results collected by users via the app were then compared against those obtained from swabs collected by healthcare professionals and tested on FDA-cleared high-complexity assays conducted in centralized laboratories by trained laboratory professionals. [IDWeek 2024, abstract 378]

The device had a sensitivity of >95 percent and a specificity of >98 percent for each of the three target organisms. Specifically, sensitivity for CT, NG, and TV was 95.2, 100, and 96.4 percent, respectively, while specificity was 99, 99.3, and 98.4 percent.

“[These results imply that the device] can provide laboratory-equivalent results for the detection of CT, NG, and TV when run by lay users at home,” said Prabhulkar.

The device has a corresponding app, which will provide video instructions on collecting a sample and running the test. Using the app, an image of the device should be taken after running the test. After which, the device will automatically read the results and generate them in PDF format. The app allows users to connect to telemedicine to facilitate consultation and appropriate treatment.

Supporting studies

A human factor usability study conducted in a simulated ‘at-home’ environment involved 140 lay users without any prior training or help. “All participants were able to successfully use the test, which validated the app user interface, workflow, and instructions,” said Prabhulkar.

She added that flex testing was also conducted to test the robustness of the device, as it is intended for home use by lay users.

Additionally, analytical studies were performed to test the assay performance of the CT, NG, and TV assays. “Limit of detection was established for the three organisms. Inclusivity, competitive interference, cross-reactivity, microbial interference, interfering substances, and specimen stability tests were conducted as well,” Prabhulkar noted.

Enhanced testing

With currently available testing strategies, patients would have to go to a clinic, submit a sample, wait several days for the results, and return for follow-up and prescriptions if necessary. The entire process may take 5?7 days.

With this novel device, the ~1-week conventional delivery time may be dialled down to about an hour or two, Prabhulkar highlighted. Self-collection of samples does not take a minute, and the results may be ready in about 30 minutes after the device runs the test. “[The goal] is to enhance a user’s journey and help them get better testing and treatment for STIs.”

“[In summary,] the device provides automated sample processing and testing, the user only needs <2 minutes of hands-on time to test their sample, and the results are true PCR test results,” said Prabhulkar.

The FDA has yet to give a green light for the in vitro use of the device. If approved, this could be “the first PCR test cleared for at-home use with the ability to offer highly accurate testing for STIs and remove barriers to promptly and accurately treating STIs,” noted Prabhulkar and colleagues.