Person: Acevedo, Johanna
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Acevedo
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Johanna
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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 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 Retrospective study on disparities in time-to-treatment by health insurance system in Chilean breast cancer patients(2025) Acevedo, Johanna; Ip, Teresa; Maureira, Lea; Sanchez, Cesar; Osorio, Claudia; Carvajal, Claudia; Rafael Araos; Araos Bralic, Rafael Ignacio; Letelier, Hernan; Acevedo, Francisco; Merino, TomasIntroduction: Breast cancer is the most common malignancy in the Americas, and the second leading cause of cancer death. Disparities in the time to treatment can significantly impact patient outcomes and typically affect lower socioeconomic individuals and/or ethnic minorities. Our study sought to evaluate disparities in time to treatment at three health institutions in Chile according to their type of health insurance (public or private). Methods: Our study analyzed a database of breast cancer patients diagnosed between 2017 and 2018. Analyses included descriptive statistics and a linear regression model that incorporated clinical and demographic variables. Additionally, using a proportional risks model, we analyzed the association between clinical variables and mortality. Results: Public health insurance (National Health Fund, FONASA) was associated with longer time-to-treatment and extended treatment times versus private health insurance (Social Security Institutions, ISAPRE; p < 0.0001). As expected, a more advanced stage at diagnosis was associated with lower survival. Our proportional risks model found that age was a predictor of breast cancer mortality in stage II patients. Also, total treatment time significantly increased the risk of breast cancer mortality in stage I patients. Conversely, total treatment time did not affect mortality on stages II or III. Conclusions: We found significant disparities in the time to treatment of Chilean breast cancer patients using FONASA versus private ISAPRE. FONASA patients experience delays in the initiation of treatment and longer total treatment times compared to their private insurance counterparts. Finally, longer time-to-treatment was associated with more advanced stages and increased mortality. INTRODUCCIÓN El cáncer de mama es la neoplasia más frecuente y la segunda causa de muerte por cáncer en el continente americano. Diferencias en los tiempos de espera al tratamiento típicamente afectan a individuos de bajo nivel socioeconómico y minorías étnicas, impactando también el pronóstico y la sobrevida. Este estudio evaluó las diferencias en tiempos de espera al tratamiento en relación al tipo de sistema de salud de los pacientes en tres instituciones de salud en Chile. MÉTODOS Se analizó una base de datos de pacientes de cáncer de mama diagnosticados entre 2017 y 2018. El análisis incluyó estadística descriptiva y un modelo de regresión lineal que consideró variables clínico-demográficas. Además la asociación entre variables clínicas y mortalidad se evaluó a través de un análisis de riesgos proporcionales RESULTADOS El sistema público de salud (Fondo Nacional de Salud, FONASA) se asoció a tiempos de espera al tratamiento más largos y tiempos totales de tratamientos más prolongados en comparación con el sistema privado (Instituciones de Salud Previsional, ISAPRES; p < 0,0001). Etapas más avanzadas al diagnóstico se asociaron a menor sobrevida. El modelo de riesgos proporcionales demostró que la edad es un predictor de mortalidad de cáncer de mama en pacientes en etapa II. Además, el tiempo total de tratamiento aumentó significativamente el riesgo de mortalidad por cáncer de mama en pacientes en etapa I. En contraste, el tiempo total de tratamiento no afectó la mortalidad en etapas II ni III. CONCLUSIONES Se encontraron diferencias significativas en el tiempo de espera al tratamiento entre pacientes Chilenas de cáncer de mama usuarias de FONASA e ISAPRES. Las pacientes de FONASA experimentaron demoras en el inicio de sus tratamientos y tiempos totales de tratamiento más prolongados en comparación a usuarias del sistema privado. Por último, tiempos de espera al tratamiento más extensos se asociaron a etapas más avanzadas y mayor mortalidad.Publication Colonization with antibiotic resistant bacteria in communities and hospitals across six countries, including Bangladesh, Botswana, Chile, Guatemala, India, and Kenya(2025) Parra, Gemma; Lautenbach, Ebbing; Mosepele, Mosepele; Mannathoko, Naledi; Gross, Robert; Call, Douglas; Ramay, Brooke; Omulo, Sylvia; Girish, C P; Bhatnagar, Tarun; Chowdhury, Fahmida; Syeda Mah-E-Muneer; Araos Bralic, Rafael Ignacio; Munita, Jose M.; Acevedo, Johanna; Mahon, Garrett; Smith, Rachel; Styczynski, AshleyThe recognized burden of antimicrobial resistance (AR) is greatest in low- and middle-income countries (LMICs), but limitations in surveillance preclude accurate estimates of AR. We aimed to evaluate colonization in communities and hospitals across six LMICs for two clinically-important pathogens: extended-spectrum cephalosporin-resistant Enterobacterales (ESCrE) and carbapenem-resistant Enterobacterales (CRE). Participants in hospitals and communities provided rectal swabs or stool samples for ESCrE and CRE identification. Isolates recovered from selective agars underwent confirmatory identification and antibiotic susceptibility testing (AST) using Vitek® 2, MALDI-TOF, and/or disc diffusion testing. ESCrE and CRE were defined based on established breakpoints of phenotypic resistance to third-generation cephalosporins and carbapenems, respectively, to calculate prevalence of colonization. Community prevalence estimates were weighted to account for sampling design differences. A total of 10,139 participants across the 6 countries provided samples; 63% were females with a median age of 35 years (range: 0-99). Colonization with ESCrE in hospitals was high in all sites (range 34-84%). In communities, ESCrE colonization ranged from 22 to 77%. Prevalence of CRE colonization in hospitals ranged from 7 to 36% and in communities ranged from < 1 to 14%. These findings reveal a high burden of AR colonization in LMICs in both communities and hospitals. Cost-effective strategies to reduce AR colonization burden are needed in LMICs.