BackgroundExpanding and providing access to early detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) through testing community-based strategies among socially vulnerable communities (SVC) are critical to reducing health disparities. The Epidemiological Intelligence Community Network (EpI-Net) community-based intervention sought to increase coronavirus 2019 (COVID-19) testing uptake and prevention practices among SVC in Puerto Rico (PR). We evaluated EpI-Net’s community leaders’ capacity-building component by assessing pre-post COVID-19 public health workshops’ tests’ score changes and satisfaction among trained community leaders.MethodsA total of 24 community leaders from SVC in PR have completed four community workshops. Pre- and post-assessments were completed as part of the health promotors training program to evaluate participants’ tests score changes and satisfaction outcomes.ResultsPreliminary results showed: (1) high intervention retention levels of community leaders (85.7% acceptance rate); (2) change in post-test scores for community engagement strategies (p = 0.012); (3) change in post-test educational scores in COVID-19 prevention practices (p = 0.014); and (4) a change in scores in public health emergency management strategies (p < 0.001).ConclusionsThe overall workshop satisfaction was 99.6%. Community leaders have shown the importance of community capacity building as a key component for intervention feasibility and impact.Trial registrationOur study was retrospectively registered under the ClinicalTrial.gov ID NCT04910542.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12889-023-15727-3.