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There is considerable interest in the waning of effectiveness of coronavirus disease 2019 (COVID-19) vaccines and vaccine effectiveness (VE) of booster doses. Using linked national Brazilian databases, we undertook a test-negative design study involving almost 14 million people (~16 million tests) to estimate VE of CoronaVac over time and VE of BNT162b2 booster vaccination against RT–PCR-confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and severe COVID-19 outcomes (hospitalization or death). Compared with unvaccinated individuals, CoronaVac VE at 14–30 d after the second dose was 55.0% (95% confidence interval (CI): 54.3–55.7) against confirmed infection and 82.1% (95% CI: 81.4–82.8) against severe outcomes. VE decreased to 34.7% (95% CI: 33.1–36.2) against infection and 72.5% (95% CI: 70.9–74.0) against severe outcomes over 180 d after the second dose. A BNT162b2 booster, 6 months after the second dose of CoronaVac, improved VE against infection to 92.7% (95% CI: 91.0−94.0) and VE against severe outcomes to 97.3% (95% CI: 96.1−98.1) 14–30 d after the booster. Compared with younger age groups, individuals 80 years of age or older had lower protection after the second dose but similar protection after the booster. Our findings support a BNT162b2 booster vaccine dose after two doses of CoronaVac, particularly for the elderly. A test-negative case–control analysis of data from Brazil shows that vaccine effectiveness against SARS-CoV-2 infection and severe COVID-19 outcomes declines after two doses of CoronaVac but increases after a booster dose of the BNT162b2 vaccine.

IntroductionChikungunya virus, an arbovirus transmitted by Aedes mosquitoes, causes epidemics in tropical regions with potential risk in higher latitudes. Our aim is to estimate the global, regional and national burden of chikungunya across affected and environmentally suitable at-risk regions.MethodsWe used a random forest model to predict force of infection and estimate chikungunya burden at high spatial resolution (5×5 km) using covariates from climatic, socioeconomic and ecological domains. We used a focal scenario to estimate the observed burden (lower bound) and an at-risk scenario to estimate the potential burden (upper bound) of chikungunya transmission.ResultsWe predicted global long-term average annual force of infection at 0.012 (95% UI: 0.007 to 0.019) for focal scenario and 0.013 (95% UI: 0.005 to 0.03) for at-risk scenario in 103 countries. We estimated global chikungunya burden annually of 14.4 million (95% UI: 11.0 to 17.8 million) infections and 0.96 million (95% UI: 0.56 to 1.6 million) disability-adjusted life years (DALYs) in the focal scenario, and 34.9 million infections (95% UI: 26.7 to 43.1 million) and 2.3 million DALYs (95% UI: 1.4 to 3.8 million) in the at-risk scenario for 2020. The chronic phase accounts for 54% of chikungunya burden, with relatively higher burden among 40–60-year-old population, with mortality disproportionately affecting children under 10 and adults over 80.ConclusionWhile chikungunya transmission has high geographical uncertainty, high force of infection is not limited to tropical regions and is distributed across all continents. Our estimates of chikungunya burden are useful for prioritisation of regions and target age groups for chikungunya vaccine introduction.

To date, no information has been published on the effectiveness of inactivated whole-virus COVID-19 vaccines plus heterologous booster against symptomatic infection and severe outcomes (hospitalization or death) during the dominance of the SARS-CoV-2 Omicron variant period. We evaluated the vaccine effectiveness (VE) of CoronaVac plus BNT162b2 booster during the period of dominance of the Omicron variant in Brazil (January to April 2022). Using a test-negative design, we analysed data for 2,471,576 individuals tested during the Omicron variant’s dominant period using a nationally linked database from Brazil. Compared to unvaccinated, vaccinees maintained protection against severe outcomes, with an estimated VE of 84.1% (95% CI:83.2–84.9) at more than 120 days after BNT162b2 booster. Furthermore, while we detected a high level of protection against severe outcomes for individuals up to 79 years old, waning was observed for individuals aged ≥80 years, with VE decreasing from 81.3% (95% CI:77.9–84.2) at 31–60 days to 72.9% (95% CI:70.6–75.1) at 120 days or more after the booster dose. However, no significant protection against symptomatic infection was observed at this time period. In conclusion, except for individuals aged ≥80 years, CoronaVac plus a BNT162b2 booster dose offered high and durable protection against severe outcomes due to Omicron. Primary CoronaVac vaccination followed by a BNT162b2 booster dose confers protection against some SARS-CoV-2 variants but its effectiveness against Omicron is unknown. Here, the authors show that this combination confers a high level of protection against severe outcomes for up to 120 days, with evidence of waning for those aged 80 or older.

Although severe COVID-19 in children is rare, they may develop multisystem inflammatory syndrome, long-COVID and downstream effects of COVID-19, including social isolation and disruption of education. Data on the effectiveness of the CoronaVac vaccine is scarce during the Omicron period. In Brazil, children between 6 to 11 years are eligible to receive the CoronaVac vaccine. We conducted a test-negative design to estimate vaccine effectiveness using 197,958 tests from January 21, 2022, to April 15, 2022, during the Omicron dominant period in Brazil among children aged 6 to 11 years. The estimated vaccine effectiveness for symptomatic infection was 39.8% (95% CI 33.7–45.4) at ≥14 days post-second dose. For hospital admission vaccine effectiveness was 59.2% (95% CI 11.3–84.5) at ≥14 days. Two doses of CoronaVac in children during the Omicron period showed low levels of protection against symptomatic infection, and modest levels against severe illness. There is limited evidence of the effectiveness of the CoronaVac vaccine for children against the Omicron SARS-CoV-2 variant. Here, the authors use data from Brazil for children aged 6–11 years and estimate effectiveness of 40% against infection and 59% against severe disease at least two weeks after the second dose.

The previous literature shows mixed conclusions regarding the risk of adverse perinatal outcomes in pregnant women with symptomatic chikungunya, dengue, and Zika. We investigated this topic using a linked population-based Brazilian cohort from 2015 to 2020. The study included 6,993,395 live births. Among these, 6066 ( < 0.1%) mothers were notified with chikungunya during pregnancy, 19,022 (0.3%) with dengue, and 8396 (0.1%) with Zika. Symptomatic maternal chikungunya was associated with an increased risk of preterm birth (Hazard ratio: 1.10, 95%CI 1.01-1.22), low Apgar score 5’ (1.44, 1.14-1.82), and neonatal death (1.50, 1.15-1.96). Symptomatic maternal dengue was associated with preterm birth (1.07, 1.02-1.12), low birth weight (1.10, 1.04-1.15), congenital anomalies (1.19, 1.03-1.37), and low Apgar score 5’ (1.26, 1.09-1.45). Symptomatic maternal Zika was associated with all adverse birth outcomes, particularly congenital anomalies, which were over twice the risk (2.36; 1.91-2.67) compared to the unexposed group. This study provides evidence of the adverse consequences of arbovirus infections during pregnancy, including critical time windows by trimester. Our findings emphasise the importance of implementing effective measures to prevent chikungunya, dengue, and Zika infections during pregnancy and the associated adverse birth and neonatal outcomes, which may have long-term health consequences for mothers and their children. In this study of ~7 million Brazilian births, the authors show that chikungunya, dengue, or Zika infection during pregnancy is associated with an increased risk of adverse perinatal outcomes, with the magnitude of these effects varying by trimester of exposure.

Brazil and Scotland have used mRNA boosters in their respective populations since September 2021, with Omicron's emergence accelerating their booster program. Despite this, both countries have reported substantial recent increases in Coronavirus Disease 2019 (COVID-19) cases. The duration of the protection conferred by the booster dose against symptomatic Omicron cases and severe outcomes is unclear. Using a test-negative design, we analyzed national databases to estimate the vaccine effectiveness (VE) of a primary series (with ChAdOx1 or BNT162b2) plus an mRNA vaccine booster (with BNT162b2 or mRNA-1273) against symptomatic Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection and severe COVID-19 outcomes (hospitalization or death) during the period of Omicron dominance in Brazil and Scotland compared to unvaccinated individuals. Additional analyses included stratification by age group (18 to 49, 50 to 64, ≥65). All individuals aged 18 years or older who reported acute respiratory illness symptoms and tested for SARS-CoV-2 infection between January 1, 2022, and April 23, 2022, in Brazil and Scotland were eligible for the study. At 14 to 29 days after the mRNA booster, the VE against symptomatic SARS-CoV-2 infection of ChAdOx1 plus BNT162b2 booster was 51.6%, (95% confidence interval (CI): [51.0, 52.2], p < 0.001) in Brazil and 67.1% (95% CI [65.5, 68.5], p < 0.001) in Scotland. At ≥4 months, protection against symptomatic infection waned to 4.2% (95% CI [0.7, 7.6], p = 0.02) in Brazil and 37.4% (95% CI [33.8, 40.9], p < 0.001) in Scotland. VE against severe outcomes in Brazil was 93.5% (95% CI [93.0, 94.0], p < 0.001) at 14 to 29 days post-booster, decreasing to 82.3% (95% CI [79.7, 84.7], p < 0.001) and 98.3% (95% CI [87.3, 99.8], p < 0.001) to 77.8% (95% CI [51.4, 89.9], p < 0.001) in Scotland for the same periods. Similar results were obtained with the primary series of BNT162b2 plus homologous booster. Potential limitations of this study were that we assumed that all cases included in the analysis were due to the Omicron variant based on the period of dominance and the limited follow-up time since the booster dose. We observed that mRNA boosters after a primary vaccination course with either mRNA or viral-vector vaccines provided modest, short-lived protection against symptomatic infection with Omicron but substantial and more sustained protection against severe COVID-19 outcomes for at least 3 months.

Chikungunya virus infection often manifests as an acute, self-limiting febrile illness, with arthralgia and musculoskeletal symptoms being the most commonly reported. Arthralgia can persist for months or even years, and approximately 50% of cases progress to chronic conditions. However, recent outbreaks have revealed a rising number of severe cases and fatalities. This review examines evidence from the past decade that suggests a higher incidence of severe chikungunya virus (CHIKV) infections and increased mortality rates, challenging official reports and guidelines from many countries. The literature review includes case reports, series, and studies with comparison groups to assess whether CHIKV-related mortality is underreported. Evaluating excess mortality involves analyzing consistent findings across different regions, biological plausibility, and systemic manifestations that contribute to severe outcomes. These findings aim to expand disease classifications in international guidelines and raise awareness among healthcare professionals to better identify severe CHIKV cases and related deaths. Studies were identified through PubMed using the search terms “chikungunya”, “death”, “severe”, “pathogenesis”, and “pathophysiology”.

Background Preterm birth and respiratory diseases disproportionately affect low-and middle-income countries. Although preterm birth is a major contributor to the burden of respiratory morbimortality in early childhood, most evidence comes from high-income settings. To address this gap, we examined respiratory-related hospitalisations and deaths among preterm children in Brazil. Methods We conducted a population-based cohort study using the CIDACS Birth Cohort, which included all live births in Brazil from January 1, 2011, to November 30, 2018. Preterm infants were defined as infants born before 37 weeks of gestation. We examined respiratory-related hospital admissions and deaths in children under five. Mean ratios (MR) and 95% confidence intervals (CI) were estimated using the Ghosh-Lin model; hazard ratios (HR) were estimated using Cox models. Maternal characteristics were adjusted through inverse probability weighting, with treatment probabilities estimated via entropy balancing. Results The study included 3,239,563 live births, with 288,466 (8.9%) classified as preterm. The MR for under-five respiratory hospitalisation, comparing preterm to term births, was 1.40 (95%CI:1.38–1.42), peaking at 1.68 (1.63–1.72) between 28 and 90 days, declining to approximately 1.18 (1.10–1.28) at the fourth year. For respiratory disease deaths, the under-five HR was 3.94 (3.62–4.30). Respiratory-related mortality was highest between 28–90 days of age, with an HR of 4.66 (4.00–5.43), decreasing to 1.25 (0.62–2.51) by three years of age. Conclusion Preterm newborns have a higher risk of respiratory illness than full-term children, particularly in their first year. This understanding can guide health strategies to address premature birth issues by identifying important periods of vulnerability.

Burnout syndrome, one of the consequences of chronic exposure to stressful, is more prevalent among physicians compared to the general population. Anesthesiology, alongside high-stress specialties such as emergency medicine and surgery, is particularly susceptible to this condition. During the COVID-19 pandemic, anesthesiologists were often on the front lines, potentially exacerbating burnout. This study aimed to assess the prevalence of burnout syndrome among Brazilian anesthesiologists during the pandemic. A cross-sectional analytical observational study was conducted with all members of the Brazilian Society of Anesthesiology (SBA). Data were collected via sociodemographic questionnaires and the Maslach Burnout Inventory (MBI), disseminated by email. Burnout syndrome was identified in 19.6% (n = 213) of respondents, while 56.5% (n = 613) were at high risk for developing burnout. Having considered quitting the specialty was the variable most strongly associated with the prevalence of burnout syndrome and the high risk of burnout. As a protective factor, dedicating more time to leisure (over 5 hours per week) was related to a lower occurrence of burnout syndrome and its risk. Burnout syndrome is highly prevalent among Brazilian anesthesiologists and residents. Target strategies to mitigate burnout should be implemented by healthcare institutions, professional organizations, and government bodies.

Chikungunya disease, caused by the chikungunya virus (CHIKV), is an acute febrile syndrome that frequently leads to chronic musculoskeletal manifestations. Little is known about the incidence, asymptomatic rate, seroconversion and chronicity after acute CHIKV infection in children and adolescents. We leveraged a nested cohort study within a phase III clinical trial of the Dengue vaccine by the Butantan Institute (DEN-03-IB), in Simões Filho (Bahia-Brazil) to characterize the dynamics of CHIKV infection in the pediatric population. 348 volunteers were included between 2018–2020 and followed for up to three years. Arbovirus surveillance was conducted during medical visits using 1) routine study visits with periodic blood collection; 2) visits due to adverse events (any symptom or illness); and 3) visits due to febrile episodes, with routine blood samples tested for chikungunya, Dengue, and Zika by viral RNA detection using RT-PCR. For cases with suspected arbovirus infection, symptoms and signs were collected with a structured questionnaire. At baseline, 7% (23/348) were positive for antichikungunya IgG. Among 311 that completed follow up (41 months, IQR 38–43), 17% tested positive for CHIKV, with 25 cases positive by RT-PCR and 28 cases by serology. 9.4% were asymptomatic and 3 (12%) developed chronic arthralgia. By the end of the study, only onefifth have been exposed to CHIKV despite several local outbreaks. Seroconversion rate among RT-PCR positive cases was 84%. Chronic arthralgia, though infrequent, was observed in the pediatric population. Our study demonstrates that, within the pediatric population, most CHIKV infections are symptomatic. We observed a small but significant frequency of negative antibody responses following acute infection and instances of chronic disease. These findings underscore the necessity for continuous surveillance and tailored interventions to tackle the unique challenges chikungunya presents in children and adolescents.