P304 The impact of active surveillance and the COVID-19 pandemic on recruitment of research participants with early syphilis in Cali, Colombia

Background Syphilis remains as a global public health threat. Understanding the immune response and the molecular variability of Tp is needed for vaccine development. However, most clinical studies do not reach their target sample size. The aim of this study was to describe our experience recruiting early syphilis cases for translational studies in Cali, Colombia. Methods The monthly number of enrolled participants (MNEP) was obtained from medical records. Three distinct periods were identified. During period 1 (July-2003 to December-2018) the study personnel visited the staff of 87 health institutions and presented the eligibility criteria. During period 2 (May-2019 to March-2020), in addition to staff visits, the active surveillance (AS) of syphilis test results was conducted and an HIV outpatient clinic (HOC) was added to the network. During period 3 (March-2020 to January-2021) the COVID-19 pandemic reached Colombia. The median and interquartile range (IQR) of the MNEP was calculated. The frequency and proportion of subjects from HIV and AS was calculated for periods 2 and 3. Finally, to assess the association between the proportion of months with 0, 1, 2, 3 or 6 participants and the period the Fisher’s exact test was used. Results 159 months were included in the analysis. The median MNEP was 1 for the three periods, while the IQR was 0–1, 1–6 and 0–2 for periods 1, 2 and 3, respectively. During period 2 only one (10%) month had zero enrolled participants and three (30%) had enrollment of six participants, while around 40% of the months of periods 1 and 3, had zero enrolled participants and none had 6 (p=0.004). During period 2 and 3, 22 (48%) participants were enrolled from AS and 6 (13%) from HOC. Conclusions Active surveillance increased the enrolment of patients with early syphilis, and potentially limited the impact of the COVID-19 pandemic.