SARS-CoV-2 testing disparities across geographical regions from a large metropolitan area in Brazil: Results from a web-based survey among individuals interested in clinical trials for COVID-19 vaccines

ABSTRACT After more than a year since the novel coronavirus (SARS-CoV-2) disease 2019 or COVID-19 has reached the status of a global pandemic, the number of COVID-19 cases continues to rise in Brazil. As no effective treatment been approved yet, only mass vaccination can stop the spread of SARS-CoV-2 and end the COVID-19 pandemic. Multiple COVID-19 vaccine candidates are under development and some are currently in use. This study aims to describe the characteristics of individuals who have registered in an online platform to participate in clinical trials for COVID-19 vaccines. Additionally, participants' characteristics according to age and presence of comorbidities associated with severe COVID-19 and differences of SARS-CoV-2 testing across different geographical areas/neighborhoods are provided. This was a cross-sectional web-based study conducted between September and December/2020, aiming to reach individuals aged ≥18 years who live in Rio de Janeiro metropolitan area, Brazil. Among 21,210 individuals who completed the survey, 20,587 (97.1%) were willing to participate in clinical trials for COVID-19 vaccines. Among those willing to participate, 57.8% individuals were aged 18-59 years and had no comorbidity, 33.7% were aged 18-59 years and had at least one comorbidity, and 8.6% were aged ≥ 60 years regardless the presence of any comorbidity. Almost half (42.6%) reported ever testing for COVID-19, and this proportion was lower among those aged ≥ 60 years (p < 0.001). Prevalence of positive PCR results was 16.0%, higher among those aged 18-59 years (p < 0.009). Prevalence of positive antibody result was 10.0%, with no difference across age and comorbidity groups. Participants from areas/neighborhoods with higher Human Development Index (HDI) reported ever testing for SARS-CoV-2 more frequently than those from lower HDI areas. Interest to participate in clinical trials for COVID-19 vaccines candidates in Rio de Janeiro was significantly high. The online registry successfully reached out a large number of individuals with diverse sociodemographic, economic and clinical backgrounds.

Population-level seropositivity trend for SARS-Cov-2 in Rio Grande do Sul, Brazil

ABSTRACT OBJECTIVE To describe the evolution of seropositivity in the State of Rio Grande do Sul, Brazil, through 10 consecutive surveys conducted between April 2020 and April 2021. METHODS Nine cities covering all regions of the State were studied, 500 households in each city. One resident in each household was randomly selected for testing. In survey rounds 1-8 we used the rapid WONDFO SARS-CoV-2 Antibody Test (Wondfo Biotech Co., Guangzhou, China). In rounds 9-10, we used a direct ELISA test that identifies IgG to the viral S protein (S-UFRJ). In terms of social distancing, individuals were asked three questions, from which we generated an exposure score using principal components analysis. RESULTS Antibody prevalence in early April 2020 was 0.07%, increasing to 10.0% in February 2021, and to 18.2% in April 2021. In round 10, self-reported whites showed the lowest seroprevalence (17.3%), while indigenous individuals presented the highest (44.4%). Seropositivity increased by 40% when comparing the most with the least exposed. CONCLUSIONS The proportion of the population already infected by SARS-Cov-2 in the state is still far from any perspective of herd immunity and the infection affects population groups in very different levels.

COVID-19 and social distancing among children and adolescents in Brazil

ABSTRACT OBJECTIVE To estimate the prevalence of SARS-CoV-2 antibodies and the adherence to measures of social distancing in children and adolescents studied in three national surveys conducted in Brazil between May-June 2020. METHODS Three national serological surveys were conducted in 133 sentinel cities located in all 27 Federative Units. Multistage probability sampling was used to select 250 individuals per city. The total sample size in age ranges 0-9 and 10-19 years old are of 4,263 and 8,024 individuals, respectively. Information on children or adolescents was gathered with a data collection app, and a rapid point-of-case test for SARS-CoV-2 was conducted on a finger prick blood sample. RESULTS The adjusted prevalence of antibodies was 2.9% (2.2-3.6) among children 0-9 years, 2.2% (1.8-2.6) among adolescents 10-19 years, and 3.0% (2.7-3.3) among adults 20+years. Prevalence of antibodies was higher among poor children and adolescents compared to those of rich families. Adherence to social distancing measures was seen in 72.4% (71.9-73.8) of families with children, 60.8% (59.6-61.9) for adolescents, and 57.4% (56.9-57.8) for adults. For not leaving the house except for essential matters the proportions were 81.7% (80.5-82.9), 70.6% (69.6-61.9), and 65.1% (64.7-65.5), respectively. Among children and adolescents, social distancing was strongly associated with socioeconomic status, being much higher in the better-off families. CONCLUSIONS The prevalence of antibodies against SARS-CoV-2 showed comparable levels among children, adolescents, and adults. Adherence to social distancing measures was more prevalent in children, followed by adolescents. There were important socioeconomic differences in the adherence to social distancing among children and adolescents.

Social distancing patterns in nine municipalities of Rio Grande do Sul, Brazil: the Epicovid19/RS study / Padrões de distanciamento social em nove cidades gaúchas: estudo Epicovid19/RS

ABSTRACT OBJECTIVE To describe social distancing practices in nine municipalities of the state of Rio Grande do Sul, Brazil, stratified by gender, age, and educational attainment. METHODS Two sequential cross-sectional studies were conducted in the municipalities of Canoas, Caxias do Sul, Ijuí, Passo Fundo, Pelotas, Porto Alegre, Santa Cruz do Sul, Santa Maria, and Uruguaiana to estimate the population prevalence of COVID-19. The study was designed to be representative of the urban population of these municipalities. A questionnaire including three questions about social distancing was also administered to the participants. Here, we present descriptive analyses of social distancing practices by subgroups and use chi-square tests for comparisons. RESULTS In terms of degree of social distancing, 25.8% of the interviewees reported being essentially isolated and 41.1% reported being quite isolated. 20.1% of respondents reported staying at home all the time, while 44.5% left only for essential activities. More than half of households reported receiving no visits from non-residents. Adults aged 20 to 59 reported the least social distancing, while more than 80% of participants aged 60 years or older reported being essentially isolated or quite isolated. Women reported more stringent distancing than men. Groups with higher educational attainment reported going out for daily activities more frequently. CONCLUSIONS The extremes of age are more protected by social distancing, but some groups remain highly exposed. This can be an important limiting factor in controlling progression of the COVID-19 pandemic.

RESUMO OBJETIVO Descrever práticas de distanciamento social em nove municípios do Rio Grande do Sul por sexo, idade, escolaridade e cidade. MÉTODOS Foram realizados dois estudos transversais sequenciais representativos da população urbana nos municípios de Canoas, Caxias do Sul, Ijuí, Passo Fundo, Pelotas, Porto Alegre, Santa Cruz do Sul, Santa Maria e Uruguaiana com o intuito de estimar a prevalência populacional de Covid-19. Foi aplicado questionário contendo três perguntas sobre distanciamento social, cujas práticas foram submetidas a análises descritivas por subgrupos. Os dados foram comparados por testes qui-quadrado. RESULTADOS Em termos de grau de distanciamento social, 25,8% dos entrevistados relataram estar praticamente isolados e 41,1% indicam praticar bastante distanciamento. Relataram ficar em casa o tempo todo 20,1% dos entrevistados, e 44,5% informam que saem apenas para atividades essenciais. Mais da metade dos domicílios não recebe visitas de não moradores. O grupo que relatou menos distanciamento social foi o de adultos entre 20 e 59 anos, enquanto mais de 80% dos entrevistados com 60 anos ou mais relataram estar praticamente isolados ou fazendo bastante distanciamento. As mulheres relataram fazer mais distanciamento que os homens, e os grupos de maior escolaridade foram os que relataram sair diariamente para atividades regulares com mais frequência. CONCLUSÕES Os grupos mais jovens e mais idosos estão mais protegidos pelo distanciamento social, mas há grupos bastante expostos, o que pode ser um limitador importante no controle da progressão da epidemia de Covid-19.

Why do we need alternative tools to control mosquito-borne diseases in Latin America?

In this opinion paper, we discuss the potential and challenges of using the symbiont Wolbachia to block mosquito transmitted diseases such as dengue, malaria and chikungunya in Latin America.

Impacto da terapia anti-retroviral na magnitude da epidemia do HIV/AIDS no Brasil: diversos cenários / Impact of antiretroviral therapy on the magnitude of the HIV/AIDS epidemic in Brazil: various scenarios

Neste trabalho, utilizaram-se os algoritmos EM e EMS aplicados ao método do Cálculo Retroativo para estimar a magnitude da epidemia do HIV no Brasil. Fazendo-se suposições a respeito do comportamento dos infectados, em relaçäo à utilizaçäo da terapia combinada das drogas anti-retrovirais, construíram-se cinco cenários para a epidemia brasileira. O objetivo foi o de ilustrar os impactos que a utilizaçäo da terapia combinada das drogas anti-retrovirais possam estar tendo ou possam vir a ter na incubaçäo do vírus e, por conseguinte, nas avaliações da epidemia realizadas a partir dos casos de Aids notificados

Estudos de agregados de doença no espaço-tempo: conceitos, técnicas e desafios / Studies on space-time disease clusters: concepts, techniques, and challenges

Os estudos de agregados espaço-temporais têm sido freqüentemente utilizados em epidemiologia e saúde pública nas últimas décadas, muitas vezes sem a adequada compreensäo de seus limites e potencialidades. O objetivo geral deste artigo é rever alguns tópicos essenciais para aprimorar a interpretaçäo e utilidade de estudos neste contexto. Inicia-se com uma discussäo sobre o significado epidemiológico do conceito de agregaçäo espaço-temporal. A seguir, descrevem-se cinco métodos analíticos, assim como os procedimentos necessários para sua utilizaçäo. Apresenta-se também uma proposta de generalizaçäo conceitual e estatística das técnicas analisadas. Por fim, discute-se uma gama de tópicos relevantes para a otimizaçäo do uso destes estudos em epidemiologia e saúde pública.

Malaria vaccines: lessons from field trials

Apresenta uma descriçäo das questoes específicas de validade que säo relevantes para uma avaliaçäo da eficácia de vacinas em campo e mostram como a aplicaçäo desses princípios poderiam melhorar a interpretaçäo dos dados coletados atualmente pelos ensaios de campo de vacinas anti-maláricas. Pressupoe que a avaliaçäo de vacinas compartilha os mesmos princípios gerais de validade com a inferência causal epidemiológica, i.é., o processo de fazer inferências a partir dos dados epidemiológicos, objetiva identificar as causas das doenças. A aplicaçäo criteriosa desses princípios indica que, as medidas de eficácia vacinal requerem definiçoes baseadas em argumentos condicionais à quantidade de exposiçäo à infecçäo e a especificaçäo dos estados inicial e final onde acredita-se que ocorre o evento de interesse para o ensaio.

Modeling AIDS vaccines: the cellular level

This paper discuses current strategies for the development of AIDS vaccines wich allow immunzation to disturb the natural course of HIV at different detailed stages of its life cycle. Mathematical models describing the main biological phenomena (i.e. virus and vaccine induced T4 cell growth; virus and vaccine induced activation latently infected T4 cells; incremental changes immune response as infection progress; antibody dependent enhancement and neutralization of infection) and allowing for different vaccination strategies serve as a backgroud for computer simulations. The mathematical models reproduce updated information on the behavior of immune cells, antibody concentrations and free viruses. The results point to some controversial outcomes of an AIDS vaccine such as an early increase in virus concentration among vaccinated when compared to nonvaccinated individuals