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Summary: Background: Temperature and rainfall patterns are known to influence seasonal patterns of dengue transmission. However, the effect of severe drought and extremely wet conditions on the timing and intensity of dengue epidemics is poorly understood. In this study, we aimed to quantify the non-linear and delayed effects of extreme hydrometeorological hazards on dengue risk by level of urbanisation in Brazil using a spatiotemporal model. Methods: We combined distributed lag non-linear models with a spatiotemporal Bayesian hierarchical model framework to determine the exposure-lag-response association between the relative risk (RR) of dengue and a drought severity index. We fit the model to monthly dengue case data for the 558 microregions of Brazil between January, 2001, and January, 2019, accounting for unobserved confounding factors, spatial autocorrelation, seasonality, and interannual variability. We assessed the variation in RR by level of urbanisation through an interaction between the drought severity index and urbanisation. We also assessed the effect of hydrometeorological hazards on dengue risk in areas with a high frequency of water supply shortages. Findings: The dataset included 12 895 293 dengue cases reported between 2001 and 2019 in Brazil. Overall, the risk of dengue increased between 0–3 months after extremely wet conditions (maximum RR at 1 month lag 1·56 [95% CI 1·41–1·73]) and 3–5 months after drought conditions (maximum RR at 4 months lag 1·43 [1·22–1·67]). Including a linear interaction between the drought severity index and level of urbanisation improved the model fit and showed the risk of dengue was higher in more rural areas than highly urbanised areas during extremely wet conditions (maximum RR 1·77 [1·32–2·37] at 0 months lag vs maximum RR 1·58 [1·39–1·81] at 2 months lag), but higher in highly urbanised areas than rural areas after extreme drought (maximum RR 1·60 [1·33–1·92] vs 1·15 [1·08–1·22], both at 4 months lag). We also found the dengue risk following extreme drought was higher in areas that had a higher frequency of water supply shortages. Interpretation: Wet conditions and extreme drought can increase the risk of dengue with different delays. The risk associated with extremely wet conditions was higher in more rural areas and the risk associated with extreme drought was exacerbated in highly urbanised areas, which have water shortages and intermittent water supply during droughts. These findings have implications for targeting mosquito control activities in poorly serviced urban areas, not only during the wet and warm season, but also during drought periods. Funding: Royal Society, Medical Research Council, Wellcome Trust, National Institutes of Health, Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro, and Conselho Nacional de Desenvolvimento Científico e Tecnológico. Translation: For the Portuguese translation of the abstract see Supplementary Materials section.

Background: Globally, incidence of dengue fever has increased more than 30-times in the past 50 years, with outbreaks becoming frequent in tropical and subtropical countries. This rapid emergence has been attributed to increased urbanisation, globalisation, international mobility, and climate change. Brazil is endemic to all four dengue virus serotypes with outbreaks occurring in every region of the country. Previous studies identified geographical barriers to dengue diffusion, with some regions of Brazil being relatively protected from outbreaks. These regions included areas in the south of the country where seasonal temperatures were too cold for vectors to efficiently transmit the virus, regions of the western Amazon that were isolated from infectious hosts and vectors, and mountainous regions of southeast Brazil. Methods: In this ecological modelling study, we used a Bayesian spatiotemporal model to understand the effect of climate variation, connectivity between cities, and socioeconomic factors, such as urbanisation, on the expansion of the permanent dengue virus transmission zone in Brazil. We obtained monthly dengue fever case data from 5560 municipalities in Brazil for 2001–19 from the Notifiable Diseases Information System (SINAN) surveillance system. The model was fitted to an outbreak indicator defined as exceeding 300 cases per 100 000 inhabitants per year. Fixed effects included climate suitability and hydrometeorological variables obtained from the Climate Research Unit (University of East Anglia, Norwich, UK), the level of influence of a city from the Brazilian Regiōes de Influência das Cidades study, and socioeconomic factors, such as urbanisation, from census data. Spatiotemporal random effects were included to account for unobserved heterogeneity, spatial autocorrelation, and temporal trends. Findings: Data from the past 10 years showed that pre-identified geographical barriers to dengue virus transmission are being eroded or destroyed completely. The emergence of dengue fever outbreaks in south Brazil coincided with an increase in the number of months per year with temperatures suitable for transmission. Interpretation: Understanding the factors that lead to the erosion of barriers to dengue virus transmission will help identify regions at risk of future outbreaks, and improve public health preparedness to emerging and re-emerging diseases. Funding: The Royal Society.

Background: There is interest in the public health impact of Long COVID, defined as symptoms that persist or begin after SARS-CoV-2 infection. We aimed to identify demographic and clinical risk factors associated with Long COVID over time in an Upper Middle-Income Country (UMIC) and potential biomarkers predictive of symptom trajectory. Methods: Prospective cohort study of adults with mild SARS-COV-2 during the Omicron period. We tracked symptom persistence and IgG antibody titers against the spike S1 subunit. Results: Of 383 participants, 276 had confirmed SARS-CoV-2 infection. Long COVID persisted for ≥ two months in 21 % and ≥ 12 months in 5 %. The most common symptoms were fatigue, upper respiratory symptoms, and myalgia/arthralgia: 15 % had fatigue for ≥ one month, 10 % for ≥ two months, and 5 % ≥ three months. Upper respiratory symptoms lasted ≥ one month in 17 %, ≥ two months in 7 %, and ≥ three months in 3 %. Fully 9 % reported myalgia/arthralgia lasting ≥ one month, 6 % ≥ two months, and 4 % ≥ three months. Risk factors for symptom persistence included female sex, not being fully vaccinated, and comorbidities. Participants experiencing persistent fatigue had lower anti-S1 IgG titers. Conclusions: In this population, symptom persistence declined after the acute phase, but 5 % of participants did not fully recover. Even in a population that was almost fully vaccinated, women, individuals with comorbidities, and the few remaining people who were unvaccinated were at greater risk for Long COVID. Immunoglobulins may have utility as a biomarker of Long COVID fatigue in this population.

Summary: Background: Incidence rates of SARS-CoV-2 infections in low-resource communities can inform vaccination strategies and non-pharmaceutical interventions (NPIs). Our objective was to estimate incidence over four epidemic waves in a slum in Rio de Janeiro, a proxy for economically deprived areas in the Global South. Methods: Prospective cohort of children and household contacts screened for SARS-CoV-2 by PCR and serology (IgG). The incidence density of PCR positive infections estimated for each wave - the first wave, Zeta, Gamma and Delta - was compared to an index combining NPIs and vaccination coverage. Findings: 718 families and 2501 individuals were enrolled, from May 2020 to November 2021. The incidence density of SARS-CoV-2 infection due to the first wave was 2, 3 times that of the other waves. The incidence among children was lower than that of older participants, except in later waves, when vaccination of the elderly reached 90%. Household agglomeration was significantly associated with incidence only during the first wave. Interpretation: The incidence of infection greatly exceeded rates reported in similar cohorts. The observed reduction in incidence in the elderly during the Delta variant wave, in spite of the rollback of NPIs, can be attributed to increased vaccine coverage. The high incidence in young people reinforces the importance of vaccination in this age group, a policy that has yet to receive the full support of some sectors of society. Funding: UK Medical Research Council, Foundation for the Advancement of Science of the State of Rio de Janeiro, National Council for Scientific and Technological Development.