Mapping the spread of SARS-CoV-2: size of the outbreak, transmission dynamics, clinical outcomes of the infection and duration of antibody responses in a small Amazonian city

The SARS-CoV-2 virus has spread globally and now represents an important challenge for low- and middle-income countries, where health infrastructure can quickly become overburdened. This proposal is part of our ongoing field research, funded by FAPESP, to investigate the epidemiology and control of SARS-CoV-2 infection in Mâncio Lima, a small Amazonian city. The general objective is to translate the information generated by the field study into evidence to guide the control of COVID-19 in one of the poorest regions of Brazil. We start from the hypothesis that many SARS-CoV-2 infections remain unnoticed and asymptomatic carriers of the infection may continue to spread the pathogen in their daily social interactions until its spontaneous elimination, becoming immune to reinfections or, at least, to serious illness. . The proposed means to test this hypothesis are: (a) to use serial serological assays to retrospectively detect seroconversion events, estimate the size of the SARS-CoV-2 outbreak and identify risk factors associated with seroconversion in the community; (b) identify social interactions and shared spaces, such as home, workplace, schools and churches, that may have contributed to the local transmission of SARS-Cov-2; (c) calculate the proportion of SARS-CoV-2 infections diagnosed retrospectively that remained asymptomatic or had mild symptoms, usually without prior diagnosis, and those associated with the disease (COVID-19), resulting in visits to health services and even even in hospitalization, and (d) determining the proportion of individuals who, when they become seropositive during the outbreak, remain with antibodies to SARS-CoV-2 over the next 12 months.