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Background: The city of Manaus, Brazil, has seen two collapses of the health system due to the COVID-19 pandemic. We report anti-SARS-CoV-2 nucleocapsid IgG antibody seroconversion rates and associated risk factors in Manaus residents before the second wave of the epidemic in Brazil. Methods: A convenience sample of adult (aged ≥18 years) residents of Manaus was recruited through online and university website advertising into the DETECTCoV-19 study cohort. The current analysis of seroconversion included a subgroup of DETECTCoV-19 participants who had at least two serum sample collections separated by at least 4 weeks between Aug 19 and Oct 2, 2020 (visit 1), and Oct 19 and Nov 27, 2020 (visit 2). Those who reported (or had no data on) having a COVID-19 diagnosis before visit 1, and who were positive for anti-SARS-CoV-2 nucleocapsid IgG antibodies at visit 1 were excluded. Using an in-house ELISA, the reactivity index (RI; calculated as the optical density ratio of the sample to the negative control) for serum anti-SARS-CoV-2 nucleocapsid IgG antibodies was measured at both visits. We calculated the incidence of seroconversion (defined as RI values ≤1·5 at visit 1 and ≥1·5 at visit 2, and a ratio >2 between the visit 2 and visit 1 RI values) during the study period, as well as incidence rate ratios (IRRs) through cluster-corrected and adjusted Poisson regression models to analyse associations between seroconversion and variables related to sociodemographic characteristics, health access, comorbidities, COVID-19 exposure, protective behaviours, and symptoms. Findings: 2496 DETECTCoV-19 cohort participants returned for a follow-up visit between Oct 19 and Nov 27, 2020, of whom 204 reported having COVID-19 before the first visit and 24 had no data regarding previous disease status. 559 participants were seropositive for anti-SARS-CoV-2 nucleocapsid IgG antibodies at baseline. Of the remaining 1709 participants who were seronegative at baseline, 71 did not meet the criteria for seroconversion and were excluded from the analyses. Among the remaining 1638 participants who were seronegative at baseline, 214 showed seroconversion at visit 2. The seroconversion incidence was 13·06% (95% CI 11·52–14·79) overall and 6·78% (5·61–8·10) for symptomatic seroconversion, over a median follow-up period of 57 days (IQR 54–61). 48·1% of seroconversion events were estimated to be asymptomatic. The sample had higher proportions of affluent and higher-educated people than those reported for the Manaus city population. In the fully adjusted and corrected model, risk factors for seroconversion before visit 2 were having a COVID-19 case in the household (IRR 1·49 [95% CI 1·21–1·83]), not wearing a mask during contact with a person with COVID-19 (1·25 [1·09–1·45]), relaxation of physical distancing (1·31 [1·05–1·64]), and having flu-like symptoms (1·79 [1·23–2·59]) or a COVID-19 diagnosis (3·57 [2·27–5·63]) between the first and second visits, whereas working remotely was associated with lower incidence (0·74 [0·56–0·97]). Interpretation: An intense infection transmission period preceded the second wave of COVID-19 in Manaus. Several modifiable behaviours increased the risk of seroconversion, including non-compliance with non-pharmaceutical interventions measures such as not wearing a mask during contact, relaxation of protective measures, and non-remote working. Increased testing in high-transmission areas is needed to provide timely information about ongoing transmission and aid appropriate implementation of transmission mitigation measures. Funding: Ministry of Education, Brazil; Fundação de Amparo à Pesquisa do Estado do Amazonas; Pan American Health Organization (PAHO)/WHO. World Health Organization Revisión por pares

Background: Twice city of Manaus located in the Brazilian rainforest, has experienced a health system collapse due to the SARS-CoV-2 pandemic. However, little is known about which groups among the general population have been more affected. In this report, we present the overall prevalence of SARS-CoV-2 infection and associated factors from the DETECTCoV-19 cohort. Methods: A convenience sampling strategy via online advertising recruited 3046 adults. Sociodemographic characteristics, COVID-19-related symptoms, COVID-19 testing, self-medication and prescribed medications were recorded. Serum anti-SARS-CoV-2 nucleocapsid IgG antibodies were measured with an in-house ELISA. Prevalence ratios (PR) were obtained using cluster-corrected and adjusted Poisson’s regression models. Findings: A crude positivity rate among asymptomatic and symptomatic individuals, was estimated at 29·10%, with a maximum seroprevalence of 41·53% corrected by test characteristics and an antibody decay rate of 27%. Regression models demonstrated a strong association towards marginalized low-income and vulnerable residents with limited health access. Presence of a COVID-19 case (PR 1·39, 1·24-1·57) or death (PR 2·14, 1·74-2·62) in a household increased greatly the risk of other household members acquiring infection. SARS-CoV-2 seroprevalence was higher among those who self-medicated to prevent infection (PR 1·36, 1·27-1·46). Interpretation: High SARS-CoV-2 seropositivity reveals a much burdensome scenario than estimations based on confirmed COVID-19 cases in Manaus. Overall, prevalence of SARS-CoV-2 antibody response demonstrated a disproportionate social and economic disparity among the study participants. The syndemic nature of COVID-19 in the Amazon region needs differential policies and urgent solutions to control the pandemic. Funding: Research was funded by Ministry of Education (MEC), Brazil. BBS, IVPF, ROS, ARCB and WBSS received scholarship from CAPES. DSSS, TBNM, MFF and NOC received scholarship from FAPEAM Declaration of Interests: The authors declare no conflict of interest. Ethics Approval Statement: The research ethics committee of Federal University of Amazonas (UFAM) approved this study (CAAE:34906920·4·0000·5020) in accordance with Brazilian law

Background: The use of corticosteroids may help control the cytokine storm occurring in acute respiratory failure due to the severe form of COVID-19. We evaluated the postacute effect of corticosteroids used during the acute phase, such as impairment in pulmonary function parameters, on day 120 (D120)-follow-up, in participants who survived over 28 days.Methods: This is a parallel, double-blind, randomized, placebo-controlled phase IIb clinical trial carried out between April 18 and October 9, 2020, conducted in hospitalized patients with clinical–radiological suspicion of COVID-19, aged 18 years or older, with SpO2 ≤ 94% on room air or requiring supplementary oxygen, or under invasive mechanical ventilation (IMV) in a referral center in Manaus, Western Brazilian Amazon. Intravenous methylprednisolone (MP) (0.5 mg/kg) was given two times daily for 5 days to these patients. The primary outcome used for this study was pulmonary function testing at day 120 follow-up visit.Results: Out of the total of surviving patients at day 28 (n = 246) from the Metcovid study, a total of 118 underwent satisfactory pulmonary function testing (62 in the placebo arm and 56 in the MP arm). The supportive treatment was similar between the placebo and MP groups (seven [11%] vs. four [7%]; P = 0.45). At hospital admission, IL-6 levels were higher in the MP group (P < 0.01). Also, the need for ICU (P = 0.06), need for IMV (P = 0.07), and creatine kinase (P = 0.05) on admission also tended to be higher in this group. In the univariate analysis, forced expiratory volume on 1st second of exhalation (FEV1) and forced vital capacity (FVC) at D120 follow-up were significantly higher in patients in the MP arm, being this last parameter also significantly higher in the multivariate analysis independently of IMV and IL-6 levels on admission.Conclusion: The use of steroids for at least 5 days in severe COVID-19 was associated with a higher FVC, which suggests that hospitalized COVID-19 patients might benefit from the use of MP in its use in the long-term, with less pulmonary restrictive functions, attributed to fibrosis.Trial Registration:ClinicalTrials.gov, Identifier: NCT04343729.