Long COVID in a Multicentric Brazilian Cohort: Acute Phase Symptom Burden and Second Booster Dose Vaccination Effects

Background: Long COVID represents a challenging medical condition. We aimed to evaluate the impact of the first and second booster doses and identify other predictors of long COVID.Methods: This was a multicentric study with two cohorts of individuals who have been infected by SARSCoV-2. A retrospective cohort composed of subjects infected between March 2020 and December 2021, and a prospective cohort composed of Healthcare Workers diagnosed between January and December 2022. Five medical centers in São Paulo and Rio de Janeiro were included. An electronic questionnaire was applied to evaluate clinical data and twelve symptoms. Long COVID was defined as the persistence or development of a new symptom beyond four weeks of infection. Predictors of Long COVID were analyzed using multivariate Logistic Regression model.Findings: Of the 1906 participants, long COVID was identified in 1280 subjects (67%). Female sex (OR 1·94 [C.I. 1·49–2·53]); three or more comorbidities (OR 2·38; [C.I. 1·01 – 5·56]); one reinfection (OR 1·54 [C.I. 1·14–2·09]); two or more reinfections (OR 2,56 [C.I. 1·06–6·15]); two to four acute symptoms (OR 9·24 [C.I. 6·52–13·11]), and five or more acute symptoms (OR 51·52 [C.I. 34·80–76·26]) were associated with increased risk of long COVID. The second booster dose was a protective factor (OR 0·45 [C.I. 0·27–0·75]) over unvaccinated individuals.Interpretation: Female sex, presence of comorbidities, number of reinfections, and particularly, number of acute symptoms were identified as independent variables for long COVID development. The second booster dose emerged as an important protective factor.Funding: Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ), and Instituto Todos pela Saúde (ITpS).Declaration of Interest: All the authors declare no competing interests.Ethical Approval: This study was approved by FMUSP’s Ethics Committee (CAAE: 42708721.0.0000.0068) and by the National Committee of Research Ethics (CAAE: 30161620.0.1001.5257). All enrolled participants were over 18 years old and declared informed consent.