BackgroundPeru had the second-highest number of COVID-19 cases in Latin America. After the first wave, Peru registered more than 900,000 cases of COVID-19 and more than 36,000 confirmed deaths from the disease. Tumbes, a border area with poor sanitation and not enough water, had the fifth highest death rate. The cross-sectional analytic study aimed: a) to assess seroprevalence of COVID-19 after the first wave; b) to assess sociodemographic determinants and symptoms associated with a positive COVID-19 antibody lateral flow test.Methodology/principal findingsWe performed this study between November 11th and November 30th, 2020, in an informal settlement in Tumbes. Individuals older than two years were invited to participate in a systematic random sample from one in every four households. Finger-prick blood samples were collected, and a census and symptom survey were applied. Within the chosen house, one adult over 18 years of age was chosen for a PCR-RT molecular test. Overall seroprevalence was 25.59%, adjusted seroprevalence was 24.82% (95%CI 22.49–27.25). Women had higher adjusted seroprevalence (28.03% vs 21.11%; 95% CI 24.83–31.41,p = 0.002). Symptoms as fever (PR 1.89: 95% CI 1.44–2.48,p<0.001), general discomfort (PR 1.67; 95% CI 1.23–2.26,p = 0.001), cough (PR 2.0; 95% CI 1.60–2.50,p<0.001), nasal congestion (PR 1.46; 95% CI 1.03–2.09,p = 0.036), respiratory distress (PR 1.64; 95% CI 1.04–2.56,p = 0.031), headache (PR 1.54; 95% CI 1.09–2.17,p = 0.014), anosmia (PR 1.78; 95% CI 1.01–3.14,p = 0.046) and ageusia (PR 2.31; 95% CI 1.48–3.61,p<0.001) were associated with a positive covid-19 antibody lateral flow test.Conclusions/significanceThe COVID-19 transmission and distribution were highlighted by this cross-sectional study. The data will help the Ministry of Health improve its monitoring, surveillance, and monitoring of respiratory community sequelae in the future.