Person: Araos Bralic, Rafael Ignacio
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Araos Bralic
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Rafael Ignacio
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Publication High Burden of Intestinal Colonization With Antimicrobial-Resistant Bacteria in Chile: An Antibiotic Resistance in Communities and Hospitals (ARCH) Study(2023) Araos Bralic, Rafael Ignacio; Smith, Rachel; Styczynski, Ashley; Sánchez, Felipe; Acevedo, Johanna; Maureira, Lea; Paredes, Catalina; González, Maite; Rivas Jiménez, Lina María; Spencer, Maria; Peters, Anne Sophie; Khan, Ayesha; Sepulveda, Dino; Rojas, Loreto; Rioseco, María; Usedo, Pedro; Rojas, Pamela; Huidobro, Laura; Ferreccio, Catterina; Park, Benjamin; Undurraga, Eduardo; D'Agata, Erika; Jara, Alejandro; Munita, Jose M.Background: Antimicrobial resistance is a global threat, heavily impacting low- and middle-income countries. This study estimated antimicrobial-resistant gram-negative bacteria (GNB) fecal colonization prevalence in hospitalized and community-dwelling adults in Chile before the coronavirus disease 2019 pandemic. Methods: From December 2018 to May 2019, we enrolled hospitalized adults in 4 public hospitals and community dwellers from central Chile, who provided fecal specimens and epidemiological information. Samples were plated onto MacConkey agar with ciprofloxacin or ceftazidime added. All recovered morphotypes were identified and characterized according to the following phenotypes: fluoroquinolone-resistant (FQR), extended-spectrum cephalosporin-resistant (ESCR), carbapenem-resistant (CR), or multidrug-resistant (MDR; as per Centers for Disease Control and Prevention criteria) GNB. Categories were not mutually exclusive. Results: A total of 775 hospitalized adults and 357 community dwellers were enrolled. Among hospitalized subjects, the prevalence of colonization with FQR, ESCR, CR, or MDR-GNB was 46.4% (95% confidence interval [CI], 42.9-50.0), 41.2% (95% CI, 37.7-44.6), 14.5% (95% CI, 12.0-16.9), and 26.3% (95% CI, 23.2-29.4). In the community, the prevalence of FQR, ESCR, CR, and MDR-GNB colonization was 39.5% (95% CI, 34.4-44.6), 28.9% (95% CI, 24.2-33.6), 5.6% (95% CI, 3.2-8.0), and 4.8% (95% CI, 2.6-7.0), respectively. Conclusions: A high burden of antimicrobial-resistant GNB colonization was observed in this sample of hospitalized and community-dwelling adults, suggesting that the community is a relevant source of antibiotic resistance. Efforts are needed to understand the relatedness between resistant strains circulating in the community and hospitals.Publication Effectiveness of an inactivated SARS-CoV-2 vaccine in children and adolescents: a large-scale observational study(2023) Jara, Alejandro; Undurraga, Eduardo; Flores, Juan; Zubizarreta, José; González, Cecilia; Pizarro, Alejandra; Ortuño, Duniel; Acevedo, Johanna; Leo, Katherinne; Paredes, Fabio; Bralic , Tomás; Vergara, Verónica; Leon, Francisco; Parot, Ignacio; Leighton, Paulina; Suárez, Pamela; Rios, Juan; García, Heriberto; Rafael Araos; Araos Bralic, Rafael IgnacioBackground: Policymakers urgently need evidence to adequately balance the costs and benefits of mass vaccination against COVID-19 across all age groups, including children and adolescents. In this study, we aim to assess the effectiveness of CoronaVac's primary series among children and adolescents in Chile. Methods: We used a large prospective national cohort of about two million children and adolescents 6-16 years to estimate the effectiveness of an inactivated SARS-CoV-2 vaccine (CoronaVac) in preventing laboratory-confirmed symptomatic SARS-CoV-2 infection (COVID-19), hospitalisation, and admission to an intensive care unit (ICU) associated with COVID-19. We compared the risk of individuals treated with a complete primary immunization schedule (two doses, 28 days apart) with the risk of unvaccinated individuals during the follow-up period. The study was conducted in Chile from June 27, 2021, to January 12, 2022, when the SARS-CoV-2 Delta variant was predominant but other variants of concern were co-circulating, including Omicron. We used inverse probability-weighted survival regression models to estimate hazard ratios of complete immunization over the unvaccinated status, accounting for time-varying vaccination exposure and adjusting for relevant demographic, socioeconomic, and clinical confounders. Findings: The estimated adjusted vaccine effectiveness for the inactivated SARS-CoV-2 vaccine in children aged 6-16 years was 74.5% (95% CI, 73.8-75.2), 91.0% (95% CI, 87.8-93.4), 93.8% (95% CI, 87.8-93.4) for the prevention of COVID-19, hospitalisation, and ICU admission, respectively. For the subgroup of children 6-11 years, the vaccine effectiveness was 75.8% (95% CI, 74.7-76.8) for the prevention of COVID-19 and 77.9% (95% CI, 61.5-87.3) for the prevention of hospitalisation. Interpretation: Our results suggest that a complete primary immunization schedule with the inactivated SARS-CoV-2 vaccine provides effective protection against severe COVID-19 disease for children 6-16 years. Funding: Agencia Nacional de Investigación y Desarrollo (ANID) Millennium Science Initiative Program and Fondo de Financiamiento de Centros de Investigación en Áreas Prioritarias (FONDAP)Publication Effectiveness of the second COVID-19 booster against Omicron: a large-scale cohort study in Chile(2023) Jara, Alejandro; Cuadrado, Cristobal; Undurraga, Eduardo; García , Christian; Nájera, Manuel; Bertoglia, María; Vergara, Verónica; Fernández , Jorge; García, Heriberto; Araos Bralic, Rafael IgnacioIn light of the ongoing COVID-19 pandemic and the emergence of new SARS-CoV-2 variants, understanding the effectiveness of various booster vaccination regimens is pivotal. In Chile, using a prospective national cohort of 3.75 million individuals aged 20 or older, we evaluate the effectiveness against COVID-19-related intensive care unit (ICU) admissions and death of mRNA-based second vaccine boosters for four different three-dose background regimes: BNT162b2 primary series followed by a homologous booster, and CoronaVac primary series followed by an mRNA booster, a homologous booster, and a ChAdOx-1 booster. We estimate the vaccine effectiveness weekly from February 14 to August 15, 2022, by determining hazard ratios of immunization over non-vaccination, accounting for relevant confounders. The overall adjusted effectiveness of a second mRNA booster shot is 88.2% (95%CI, 86.2-89.9) against ICU admissions and 90.5% (95%CI 89.4-91.4) against death. Vaccine effectiveness shows a mild decrease for all regimens and outcomes, probably linked to the introduction of BA.4 and BA.5 Omicron sub-lineages and the waning of immunity. Based on our findings, individuals might not need additional boosters for at least 6 months after receiving a second mRNA booster shot in this setting. A la luz de la actual pandemia de COVID-19 y la aparición de nuevas variantes del SARS-CoV-2, es fundamental comprender la eficacia de varios regímenes de vacunación de refuerzo. En Chile, utilizando una cohorte nacional prospectiva de 3,75 millones de personas de 20 años o más, evaluamos la efectividad contra las admisiones a unidades de cuidados intensivos (UCI) relacionadas con COVID-19 y la muerte de segundas dosis de refuerzo basadas en ARNm para cuatro dosis diferentes de tres dosis. regímenes: serie primaria BNT162b2 seguida de un refuerzo homólogo, y serie primaria CoronaVac seguida de un refuerzo de ARNm, un refuerzo homólogo y un refuerzo de ChAdOx-1. Estimamos la efectividad de la vacuna semanalmente del 14 de febrero al 15 de agosto de 2022, determinando los índices de riesgo de inmunización frente a no vacunación, teniendo en cuenta los factores de confusión relevantes. La eficacia global ajustada de una segunda inyección de refuerzo de ARNm es del 88,2% (IC del 95%, 86,2-89,9) frente a los ingresos en la UCI y del 90,5% (IC del 95%, 89,4-91,4) frente a la muerte. La eficacia de la vacuna muestra una leve disminución en todos los regímenes y resultados, probablemente relacionada con la introducción de los sublinajes Omicron BA.4 y BA.5 y la disminución de la inmunidad. Según nuestros hallazgos, es posible que las personas no necesiten refuerzos adicionales durante al menos 6 meses después de recibir una segunda inyección de refuerzo de ARNm en este entorno.