Protocol for an ambidirectional cohort study on long COVID and the healthcare needs, use and barriers to access health services in a large city in Southeast Brazil.

introductionPost-COVID-19 condition, or syndrome, also known as long COVID, is an infection-associated chronic condition that can develop after a SARS-CoV-2 infection and last at least 3 months to years. Despite representing a high burden for the Unified Health System (SUS), which has affected millions of Brazilians, it has received limited attention in Brazil. Prevalence studies to date have failed to include a broad representation of the population, and there has been insufficient exploration of the impact on people's lives and the burden of and barriers to accessing health services. This article presents the research protocol for the quantitative component of a mixed methods project to produce evidence to inform SUS's provision of care for long COVID. The protocol was designed to study long COVID in SUS patients hospitalised for COVID-19 in a large city in Southeast Brazil to capture symptoms and factors associated with the syndrome, effects on quality of life and employment, health needs, use of health services and barriers to accessing necessary healthcare. METHODS AND ANALYSIS: An ambidirectional cohort study to capture data retrospectively and prospectively from adults previously discharged from SUS hospitals for COVID-19. The study involves up to two telephone surveys with the patients or proxies selected from a sampling plan for population estimates. Survey questions include baseline and follow-up data on demographic, socioeconomic, comorbidities, work status, health-related quality of life, vaccination status, long COVID symptoms, healthcare needs, use and barriers to access. Descriptive and appropriate multivariable analyses will be employed. ETHICS AND DISSEMINATION: The project was approved by the Research Ethics Committees of participant institutions and by the Brazilian National Research Ethics Commission. All participants provided verbal consent. We plan to publish articles in scientific journals and multimedia resources for SUS professionals and the general population.