Seroepidemiological monitoring of SARS-CoV-2 IgG in main railway stations in the city of Buenos Aires, Argentina

Abstract

INTRODUCTION: Seroprevalence studies allow monitoring the circulation of SARS-CoV-2, providing information to evaluate public health measures. The aim of this study was to determine the proportion and evolution of seropositivity in high circulation points in the Ciudad Autónoma de Buenos Aires (CABA) and clinical and epidemiological characteristics of seropositive individuals from April to October 2020. METHODS: A descriptive cross-sectional study was conducted during six rounds, using rapid serological testing together with an epidemiological data survey. A convenience sample was selected in three CABA railway stations considered as high bi-directional traffic points in the Buenos Aires Metropolitan Area (AMBA). RESULTS: 7,339 people participated. The seropositive proportion was 0.6% (95%CI: 0.2-0.9) in the first round, and rose to 5.6% in the last one (95%CI: 4.3-7). Initially, seropositivity increased in CABA residents and those living in the southern part of the Buenos Aires Metropolitan Region. Having presented symptoms and history of contact with COVID-19 cases were the only variables found to be related to positive IgG results (p<0.05). Among seropositive participantes, 56.1% (n=97) had no symptoms and 78.4% (n=134) didn’t receive a COVID-19 diagnosis in the acute stage. DISCUSSION: Seropositivity increased between rounds, according to the epidemiological situation in the area of residence. Epidemiological characteristics, such as the proportion of seropositive individuals with no history of symptoms, reaffirm the importance of public health and social measures.