Population-based seroprevalence of SARS-CoV-2 and the herd immunity threshold in Maranhão

ABSTRACT OBJECTIVE: To estimate the seroprevalence of SARS-CoV-2 in the state of Maranhão, Brazil. METHODS: A population-based household survey was performed, from July 27, 2020 to August 8, 2020. The estimates considered clustering, stratification and non-response. Qualitative detection of IgM and IgG antibodies was performed in a fully-automated Elecsys® Anti-SARS-CoV-2 electrochemiluminescence immunoassay on the Cobas® e601 analyzer (Roche Diagnostics). RESULTS: In total, 3,156 individuals were interviewed. Seroprevalence of total antibodies against SARS-CoV-2 was 40.4% (95%CI 35.6-45.3). Population adherence to non-pharmaceutical interventions was higher at the beginning of the pandemic than in the last month. SARS-CoV-2 infection rates were significantly lower among mask wearers and among those who maintained social and physical distancing in the last month compared to their counterparts. Among the infected, 26.0% were asymptomatic. The infection fatality rate (IFR) was 0.14%, higher for men and older adults. The IFR based on excess deaths was 0.28%. The ratio of estimated infections to reported cases was 22.2. CONCLUSIONS: To the best of our knowledge, the seroprevalence of SARS-CoV-2 estimated in this population-based survey is one of the highest reported. The local herd immunity threshold may have been reached or might be reached soon.

Trend analysis of leprosy indicators in a hyperendemic Brazilian state, 2001-2015 / Análise da tendência dos indicadores da hanseníase em estado brasileiro hiperendêmico, 2001-2015

ABSTRACT OBJECTIVE To analyze the temporal trend of leprosy indicators in a hyperendemic state of Brazil, from 2001-2015. METHODS This is a time-series study of leprosy indicators in the state of Maranhão, Northeastern region of Brazil. The study used data from the Brazilian National System of Reportable Diseases, for the period between 2001 and 2015. The following indicators were evaluated: (i) detection coefficient in the general population; (ii) detection coefficient in people under 15 years old; (iii) rate of cases with grade 2 physical disability in the diagnosis; (iv) rate of examined contacts, and (v) proportion of healing . The Prais-Winsten regression model was used for trend analysis. Analyses were performed for the state and by each health region. RESULTS 77,697 leprosy cases were analyzed in the general population and 7,599 in individuals under 15 years old. The detection coefficient in the general population ranged from 80.7/100 thousand inhabitants in 2001 to 51.2/100 thousand inhabitants in 2015. The coefficient in the general population presented a downward trend (annual percentage variation [APV] = -2.98; 95%CI -4.15- -1.79). For the population under 15 years old, the rate was 24.9/100 thousand inhabitants in 2001, and 19.9/100 thousand inhabitants in 2015, with downward trend (APV = -3.07; 95%CI -4.95- -1.15). It was observed upward trend in rate of contacts examined (APV = 2.35; 95%CI 0.58-4.15) and rate of cases with grade 2 disability (APV = 2.19; 95%CI 0.23-4.19). Stationary trend was observed in the proportion of healing (APV = -0.10; 95%CI -0.50-0.30). Regional differences were found in the performance of the indicators. CONCLUSIONS A downward trend for the detection coefficients in the general population and in individuals under 15 years old was found in Maranhão. Despite this result, the rates are still very high, demanding efforts from all spheres of public administration and health professionals to reduce the burden of the disease in the state.

RESUMO OBJETIVO Analisar a tendência temporal dos indicadores da hanseníase em estado brasileiro hiperendêmico, no período de 2011 a 2015. MÉTODOS Trata-se de um estudo de série temporal dos indicadores de hanseníase no estado do Maranhão, região Nordeste, que utilizou dados do Sistema Nacional de Agravos de Notificação, no período de 2001 a 2015. Foram avaliados os seguintes indicadores: (i) coeficiente de detecção na população em geral; (ii) coeficiente de detecção em menores de 15 anos; (iii) proporção de casos com grau 2 de incapacidade física no diagnóstico; (iv) proporção de contatos examinados e (v) proporção de cura. Para análise da tendência foi utilizado o modelo de regressão de Prais Winsten . As análises foram realizadas para o Estado e por região de saúde. RESULTADOS Foram analisados 77.697 casos de hanseníase na população geral e 7.599 em menores de 15 anos. O coeficiente de detecção na população geral variou de 80,7/100 mil habitantes em 2001 para 51,2/100 mil habitantes em 2015. Verificou-se tendência decrescente do coeficiente na população geral (variação percentual anual [VPA] = -2,98; IC95% -4,15- -1,79). Na população menor de 15 anos, o coeficiente foi de 24,9/100 mil habitantes em 2001 para 19,9/100 mil habitantes em 2015, com tendência decrescente (VPA = -3,07; IC95% -4,95- -1,15). Observou-se tendência crescente na proporção de contatos examinados (VPA = 2,35; IC95%: 0,58-4,15) e na proporção de casos com grau 2 de incapacidade (VPA = 2,19; IC95% 0,23-4,19). Verificou-se tendência estacionária na proporção de cura de hanseníase (VPA = -0,10; IC95% -0,50-0,30). Observaram-se diferenças regionais no desempenho dos indicadores. CONCLUSÕES A tendência dos coeficientes de detecção na população geral e em menores de 15 anos mostrou-se decrescente no Maranhão. Apesar disso, as taxas ainda são muito elevadas, o que exige esforços de todas as esferas de gestão e profissionais da saúde para redução da carga da doença no estado.