Specimen Collection and Analysis
WEST
Clinical staff collected a lateral vaginal wall swab from participants at each follow-up visit; swabs were stored dry at − 80 °C until analysis. We analysed swabs collected at the month six and final study visits for PSA at the University of North Carolina at Chapel Hill (UNC). Trained laboratory staff eluted lateral vaginal wall swabs into phosphate-buffered saline and centrifuged suspensions to separate cellular material and soluble contents (including PSA) in the supernatant using Isohelix Spin + Collect SC150-SPIN Devices. Eluate was diluted 1:10 with PBS and tested for PSA using the ABAcard p30 rapid immunochromatographic strip test (Abacus Diagnostics, West Hill, CA; lower limit of detection 4 ng PSA/ml) as previously described [