'REBRACOVID' - multicentre cohort study of the natural history and immunology of COVID-19 in Brazil

COVID-19 disease cohorts have been recruited and studied in many parts of the world in recent months, but there is still much to learn. There is a specific and urgent need to better understand this disease in Brazil: WHO data places Brazil 2nd in the world for
COVID-19 cases and deaths, and the country faces challenges of urban crowding (including favelas), socioeconomic disparities, and a healthcare system stretched by disease burden including the mosquito-borne infections. Our aim here is to collect and
analyse disease parameters in a large disease cohort of hospitalised and community cases, from 9 centres across the country. In doing so, we benefit also from building a consortium that bolts-on to our established consortium studies, REPLICK (Brazil) and
SPIICA (Anglo-Brazil, MRC-Newton), designed to conduct analogous cohort studies in relation to the immunopathology and chronic disease phenotype in infection by Chikungunya virus - a mosquito-borne infection that can also lead to chronic disease
symptoms. We aim to recruit a cohort of 20,000 total infected patients, as well as household contacts and at-risk healthcare workers. Our data will allow us to define impacts of age, gender, occupation, ethnicity, other health conditions, socio-economic
factors, blood markers and importantly, measures of protective immunity and its durability. Our intention is to better understand susceptibility and mechanisms underlying this disease, drawing on specific insights from the serious situation in Brazil to impact local
management of the response.

While a number of COVID-19 cohort disease demographic and mechanism studies are in progress, many unknowns remain, and each setting has offered distinctive insights. The clinical imperative to better understand the specific challenges in Brazil is strong: WHO data places Brazil 2nd in the world for COVID-19 cases and deaths. Furthermore, this huge country poses challenges of urban crowding and socioeconomic disparities and a healthcare system stretched by disease burden. On a COVID-19 disease trajectory lagging about 1-month behind Europe, there is potential to establish a large cohort during acute disease, taking into account mechanistic insights already gained. In doing so, we benefit also from building a consortium that bolts-on to our established consortium, international,collaborative studies, REPLICK (Brazil) and SPIICA (Anglo-Brazil, MRCNewton ref MR/S019553/1), designed to conduct analogous cohort studies in relation to the immunopathology and chronic disease phenotype in Chikungunya virus infection. We aim to recruit a cohort of 20,000 total infected, PCR+ COVID-19 cases from 9 centres across Brazil, as well as household contacts and healthcare workers. We will characterise basic demographics of those affected, including impacts of age, gender, occupation, ethnicity, co-morbidities, socio-economic factors, blood biochemistry, antibody and T cell immunity (and durability), CT findings, as well as defining chronic sequelae. We will also
investigate treatment modalities and co-infections in relation to disease outcome. Communication of findings from this cohort study will be valuable to inform management of the pandemic in Brazil and elsewhere