ARAOS BRALIC, RAFAEL IGNACIO
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ARAOS BRALIC, RAFAEL IGNACIO
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rafaelaraos@udd.cl
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34976138500

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Effectiveness of CoronaVac in children 3–5 years of age during the SARS-CoV-2 Omicron outbreak in Chile

2022 , Alejandro Jara , Eduardo A. Undurraga , José R. Zubizarreta , Cecilia González , ACEVEDO ROMO, JOHANNA PATRICIA , Alejandra Pizarro , Verónica Vergara , Mario Soto-Marchant , Rosario Gilabert , Juan Carlos Flores , Pamela Suárez , Paulina Leighton , Pablo Eguiguren , Juan Carlos Ríos , Jorge Fernandez , Heriberto García-Escorza , ARAOS BRALIC, RAFAEL IGNACIO

AbstractThe outbreak of the B.1.1.529 lineage of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (Omicron) has caused an unprecedented number of Coronavirus Disease 2019 (COVID-19) cases, including pediatric hospital admissions. Policymakers urgently need evidence of vaccine effectiveness in children to balance the costs and benefits of vaccination campaigns, but, to date, the evidence is sparse. Leveraging a population-based cohort in Chile of 490,694 children aged 3–5 years, we estimated the effectiveness of administering a two-dose schedule, 28 days apart, of Sinovac’s inactivated SARS-CoV-2 vaccine (CoronaVac). We used inverse probability-weighted survival regression models to estimate hazard ratios of symptomatic COVID-19, hospitalization and admission to an intensive care unit (ICU) for children with complete immunization over non-vaccination, accounting for time-varying vaccination exposure and relevant confounders. The study was conducted between 6 December 2021 and 26 February 2022, during the Omicron outbreak in Chile. The estimated vaccine effectiveness was 38.2% (95% confidence interval (CI), 36.5–39.9) against symptomatic COVID-19, 64.6% (95% CI, 49.6–75.2) against hospitalization and 69.0% (95% CI, 18.6–88.2) against ICU admission. The effectiveness against symptomatic COVID-19 was modest; however, protection against severe disease was high. These results support vaccination of children aged 3–5 years to prevent severe illness and associated complications and highlight the importance of maintaining layered protections against SARS-CoV-2 infection.

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Tool for Estimating the Probability of Having COVID-19 With 1 or More Negative RT-PCR Results

2021 , Alejandro Jara , Eduardo A Undurraga , ARAOS BRALIC, RAFAEL IGNACIO

Abstract Early case detection and isolation of infected individuals are critical to controlling coronavirus disease 2019 (COVID-19). Reverse transcription polymerase chain reaction (RT-PCR) is considered the gold standard for the diagnosis of severe acute respiratory syndrome coronavirus 2 infection, but false negatives do occur. We built a user-friendly online tool to estimate the probability of having COVID-19 with negative RT-PCR results and thus avoid preventable transmission.

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Neutralizing antibodies induced by homologous and heterologous boosters in CoronaVac vaccines in Chile

2023 , ACEVEDO ROMO, JOHANNA PATRICIA , Mónica L. Acevedo , Aracelly Gaete-Argel , ARAOS BRALIC, RAFAEL IGNACIO , Cecilia Gonzalez , Daniela Espinoza , Pablo Pizarro , RIVAS VERA, SOLANGE VERÓNICA , Stephan Jarpa , Ricardo Soto-Rifo , Alejandro Jara , Fernando Valiente-Echeverría

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Effectiveness of the second COVID-19 booster against Omicron: a large-scale cohort study in Chile

2023 , Alejandro Jara , Cristobal Cuadrado , Eduardo A. Undurraga , Christian García , Manuel Nájera , María Paz Bertoglia , Verónica Vergara , Jorge Fernández , Heriberto García-Escorza , ARAOS BRALIC, RAFAEL IGNACIO

AbstractIn 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.

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Effectiveness of an inactivated SARS-CoV-2 vaccine in children and adolescents: a large-scale observational study

2023 , Alejandro Jara , Eduardo A. Undurraga , Juan Carlos Flores , José R. Zubizarreta , Cecilia González , Alejandra Pizarro , Duniel Ortuño-Borroto , ACEVEDO ROMO, JOHANNA PATRICIA , Katherinne Leo , Fabio Paredes , Tomás Bralic , Verónica Vergara , Francisco Leon , Ignacio Parot , Paulina Leighton , Pamela Suárez , Juan Carlos Rios , Heriberto García-Escorza , ARAOS BRALIC, RAFAEL IGNACIO

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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 , Rachel M Smith , Ashley Styczynski , Felipe Sánchez , Lea Maureira , ACEVEDO ROMO, JOHANNA PATRICIA , Catalina Paredes , Maite González , RIVAS JIMENEZ, LINA MARIA , Maria Spencer-Sandino , Anne Peters , Ayesha Khan , Dino Sepulveda , Loreto Rojas Wettig , María Luisa Rioseco , Pedro Usedo , Pamela Rojas Soto , Laura Andrea Huidobro , Catterina Ferreccio , Benjamin J Park , Eduardo Undurraga , Erika M C D’Agata , Alejandro Jara , MUNITA SEPULVEDA, JOSE MANUEL

Abstract 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.

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Effectiveness of an Inactivated SARS-CoV-2 Vaccine in Chile

2021 , Alejandro Jara , Eduardo A. Undurraga , Cecilia González , Fabio Paredes , Tomás Fontecilla , Gonzalo Jara , Alejandra Pizarro , ACEVEDO ROMO, JOHANNA PATRICIA , Katherinne Leo , Francisco Leon , Carlos Sans , Paulina Leighton , Pamela Suárez , Heriberto García-Escorza , ARAOS BRALIC, RAFAEL IGNACIO

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Effectiveness of homologous and heterologous booster doses for an inactivated SARS-CoV-2 vaccine: a large-scale prospective cohort study

2022 , Alejandro Jara , Eduardo A Undurraga , José R Zubizarreta , Cecilia González , Alejandra Pizarro , Johanna Acevedo , Katherinne Leo , Fabio Paredes , Tomás Bralic , Verónica Vergara , Marcelo Mosso , Francisco Leon , Ignacio Parot , Paulina Leighton , Pamela Suárez , Juan Carlos Rios , Heriberto García-Escorza , ARAOS BRALIC, RAFAEL IGNACIO

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