Clinical and Microbiological Characteristics of Febrile Neutropenia During Induction Chemotherapy in Adults With Acute Leukemia.

BACKGROUND: Few studies regarding infectious causes of febrile neutropenia (FN) in Mexico are available. AIMS: We aimed to describe clinical and microbiological characteristics of FN episodes during induction chemotherapy in adults with acute leukemia. METHODS AND RESULTS: This retrospective cohort from a Mexican tertiary care center included adults with newly diagnosed acute leukemia between January 2014, and December 2018. Clinical and microbiological characteristics were summarized using descriptive statistics. Univariate analyses for associations between clinical characteristics and FN and/or death were made; logistic regression analysis was performed to assess relationships with FN. Kaplan-Meier survival estimates were modeled for antimicrobial prophylaxis and FN. Ninety-five patients were included. Median age was 28 (IQR 20-43), 49 (52%) were males, and 74 (78%) developed FN (74/95). Among these, 98% had an identified source of infection (73/74) and 65% had >1. Common infections were urinary tract infection (24%), bacterial sinusitis (20%), and bacterial pneumonia (19%). Gram-negatives were the most frequently isolated microorganisms (69%), followed by Gram-positives (21%), and fungi (9%). Antimicrobial prophylaxis was inversely associated with FN (aOR = 0.07, CI 0.008-0.060, p = 0.02). Invasive fungal diseases were associated with 30-day mortality (aOR = 9.46, 95% CI 1.66-54.05). CONCLUSION: Infections caused 98% of the FN episodes. Gram-negative bacteria are the most common pathogens.

Nirmatrelvir/ritonavir and remdesivir against symptomatic treatment in high-risk COVID-19 outpatients to prevent hospitalization or death during the Omicron era: a propensity score-matched study.

Background: Even though worldwide death rates from coronavirus disease 2019 (COVID-19) have decreased, the threat of disease progression and death for high-risk groups continues. Few direct comparisons between the available severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antivirals have been made. Objective: We aimed to compare two SARS-CoV-2 antivirals (nirmatrelvir/ritonavir and remdesivir) against all-cause hospitalization or death. Design: This is a propensity score-matched cohort study. Methods: We included all high-risk outpatients with COVID-19 in a tertiary referral center in Mexico City from 1 January 2022 to 31 July 2023. The primary outcome was all-cause hospitalization or death 28 days after symptom onset. The secondary outcome was COVID-19-associated hospitalization or death 28 days after symptom onset. Logistic regression analysis for characteristics associated with the primary outcome and a multi-group comparison with Kaplan-Meier survival estimates were performed. Results: Of 1566 patients analyzed, 783 did not receive antiviral treatment, 451 received remdesivir, and 332 received nirmatrelvir/ritonavir. The median age was 60 years (interquartile range: 46-72), 62.5% were female and 97.8% had at least one comorbidity. The use of nirmatrelvir/ritonavir was associated with an absolute risk reduction of 8.8% and a relative risk reduction of 90% for all-cause hospitalization or death. The use of remdesivir was associated with an absolute risk reduction of 6.4% and a relative risk reduction of 66% for all-cause hospitalization or death. In multivariable analysis, both antivirals reduced the odds of 28-day all-cause hospitalization or death [nirmatrelvir/ritonavir odds ratio (OR) 0.08 - 95% confidence interval (CI): 0.03-0.19, remdesivir OR 0.29 - 95% CI: 0.18-0.45]. Conclusion: In high-risk COVID-19 outpatients, early antiviral treatment with nirmatrelvir/ritonavir or remdesivir was associated with lower 28-day all-cause hospitalization or death.

Nirmatrelvir/ritonavir and remdesivir against symptomatic treatment in high-risk COVID-19 outpatients In this study, we included high-risk non-hospitalized patients with confirmed mild COVID-19. We compared those who received antiviral treatment (nirmatrelvir/ritonavir or remdesivir) against those who only received symptomatic treatment. The aim was to detect differences in hospitalization or death 28 days after symptom onset. We analyzed 1566 patients: 783 did not receive antiviral treatment, 451 received remdesivir, and 332 received nirmatrelvir/ritonavir. Most patients were female and over 60 years old. The most common comorbidities were chronic hypertension (44%), diabetes mellitus (26%), and autoimmune diseases (25%); systemic immunosuppression was registered in 35% of patients. Hospitalization or death 28 days after symptom onset occurred in 168 patients (136 in the symptomatic treatment group, 27 in the remdesivir group, and 5 in the nirmatrelvir/ritonavir group). Considering multiple variables like age, sex, comorbidities, and previous vaccination, both antivirals significantly reduced the odds of hospitalization or death (nirmatrelvir/ritonavir odds ratio 0.08, 95% confidence interval 0.03-0.19; remdesivir odds ratio 0.29, 95% confidence interval 0.18-0.45).

Cephalotin Versus Dicloxacillin for the Treatment of Methicillin-Susceptible Staphylococcus aureus Bacteraemia: A Retrospective Cohort Study.

BACKGROUND: First-line treatments for methicillin-susceptible S. aureus (MSSA) bacteraemia are nafcillin, oxacillin, or cefazolin. Regional shortages of these antibiotics force clinicians to use other options like dicloxacillin and cephalotin. This study aims to describe and compare the safety and efficacy of cephalotin and dicloxacillin for the treatment of MSSA bacteraemia. METHODS: This retrospective study was conducted in a referral centre in Mexico City. We identified MSSA isolates in blood cultures from 1 January 2012 to 31 December 2022. Patients ≥ 18 years of age, with a first episode of MSSA bacteraemia, who received cephalotin or dicloxacillin as the definitive antibiotic treatment, were included. The primary outcome was in-hospital all-cause mortality. RESULTS: We included 202 patients, of which 48% (97/202) received cephalotin as the definitive therapy and 52% (105/202) received dicloxacillin. In-hospital all-cause mortality was 20.7% (42/202). There were no differences in all-cause in-hospital mortality between patients receiving cephalotin or dicloxacillin (20% vs. 21%, p = 0.43), nor in 30-day all-cause mortality (14% vs. 18%, p = 0.57) or 90-day all-cause mortality (24% vs. 22%, p = 0.82). No severe adverse reactions were associated with either antibiotic. CONCLUSIONS: Cephalotin and dicloxacillin were equally effective for treating MSSA bacteraemia, and both showed an adequate safety profile.

Why are you hitting yourself? Whole-exome sequencing diagnosis of monogenic autoimmunity.

Inborn errors of immunity may present with autoimmunity and autoinflammation as hallmark clinical manifestations. We aimed to identify the potential monogenic causes of autoimmune disorders in 26 patients from a pediatric reference hospital in Mexico through whole-exome sequencing. We specifically selected patients with a family history of autoimmune diseases, early-onset symptoms, and difficult-to-control autoimmune disorders or autoimmunity associated with infection predisposition. We identified the genetic variants that were compatible with the patients' phenotype in 54% of the patients. Autoimmune diseases are often caused by a combination of genetic factors, but cases that appear at a young age are resistant to treatment or occur in clusters, as well as the presence of autoimmune symptoms alongside infectious diseases should raise suspicion for an underlying inborn error of immunity.

Clinical, molecular, and histological characteristics of severely necrotic and fatal mpox in HIV-infected patients.

BACKGROUND: This case series of 5 patients with severely necrotic mpox highlights the predominantly necrotic nature of lesions seen in cases of severe mpox as shown by skin and lung biopsy, as well as the extensive dissemination of the infection, as shown by polymerase chain reaction (PCR) assessment in different body sites. CASE PRESENTATIONS: Patients were male, the median age was 37, all lived with HIV (2 previously undiagnosed), the median CD4+ cell count was 106 cells/mm3, and 2/5 were not receiving antiretroviral treatment. The most common complication was soft tissue infection. Skin and lung biopsies showed extensive areas of necrosis. Mpox PCR was positive in various sites, including skin, urine, serum, and cerebrospinal fluid. The initiation of antiretroviral treatment, worsened the disease, like that seen in immune reconstitution syndrome. Three patients died due to multiple organ failure, presumably associated with mpox since coinfections and opportunistic pathogens were ruled out. CONCLUSIONS: Severely necrotic manifestations of mpox in people living with advanced and untreated HIV are related to adverse outcomes.

Risk Factors Associated with the Development of Hospital-Acquired Infections in Hospitalized Patients with Severe COVID-19.

Recognition of risk factors for hospital-acquired infections (HAI) in patients with COVID-19 is warranted. We aimed to describe factors associated with the development of HAI in patients with severe COVID-19. We conducted a retrospective cohort study including all adult patients admitted with severe COVID-19 between March 2020 and November 2020. The primary outcome was HAI development. Bivariate and multiple logistic regression models were constructed. Among 1540 patients, HAI occurred in 221 (14%). A total of 299 episodes of HAI were registered. The most common HAI were hospital-acquired/ventilation-associated pneumonia (173 episodes) and primary bloodstream infection (66 episodes). Death occurred in 387 (35%) patients and was more frequent in patients with HAI (38% vs. 23%, p < 0.01). Early mechanical ventilation (aOR 18.78, 95% CI 12.56-28.07), chronic kidney disease (aOR 3.41, 95% CI 1.4-8.27), use of corticosteroids (aOR 2.95, 95% CI 1.92-4.53) and tocilizumab (aOR 2.68, 95% CI 1.38-5.22), age ≥ 60 years (aOR 1.91, 95% CI 1.27-2.88), male sex (aOR 1.52, 95% CI 1.03-2.24), and obesity (aOR 1.49, 95% CI 1.03-2.15) were associated with HAI. In patients with severe COVID-19, mechanical ventilation within the first 24 h upon admission, chronic kidney disease, use of corticosteroids, use of tocilizumab, age ≥ 60 years, male sex, and obesity were associated with a higher risk of HAI.

Predictors of Mortality in Patients with Infections Due to Carbapenem-Resistant Gram-Negative Bacteria.

INTRODUCTION: Infections caused by carbapenem-resistant Gram-negative bacteria (CR-GNB) are a significant cause of mortality and represent a serious challenge to health systems. The early identification of mortality predictors could guide appropriate treatment and follow-up. We aimed to identify the factors associated with 90-day all-cause mortality in patients with CR-GNB infections. METHODS: We conducted a cohort study from 1 January 2019 to 30 April 2022. The primary outcome was death from any cause during the first 90 days after the date of the first CR-GNB-positive culture. Secondary outcomes included infection relapse, invasive mechanical ventilation during follow-up, need for additional source control, acute kidney injury, Clostridioides difficile infection, and all-cause hospital admission after initial discharge. Bivariate and multivariate Cox-proportional hazards models were constructed to identify the factors independently associated with 90-day all-cause mortality. RESULTS: A total of 225 patients with CR-GNB infections were included. Death occurred in 76 (34%) cases. The most-reported comorbidities were immunosuppression (43%), arterial hypertension (35%), and COVID-19 (25%). The median length of stay in survivors was 18 days (IQR 10-34). Mechanical ventilation and ICU admission after diagnosis occurred in 8% and 11% of cases, respectively. Both infection relapse and rehospitalisation occurred in 18% of cases. C. difficile infection was diagnosed in 4% of cases. Acute kidney injury was documented in 22% of patients. Mechanical ventilation after diagnosis, ICU admission after diagnosis, and acute kidney injury in the first ten days of appropriate treatment were more frequently reported among non-survivors. In the multivariate analysis, age (HR 1.19 (95%CI 1.00-1.83)), immunosuppression (HR 1.84 (95%CI 1.06-3.18)), and septic shock at diagnosis (HR 2.40 (95% 1.41-4.08)) had an independent association with death during the first 90 days after the CR-GNB infection diagnosis. Receiving antibiogram-guided appropriate treatment was independently associated with a lower risk of death (HR 0.25 (95%CI 0.14-0.46)). CONCLUSIONS: The presence of advanced age, immunosuppression, septic shock at diagnosis, and inappropriate treatment are associated with higher 90-day all-cause mortality in hospitalised patients with infections due to CR-GNB. Recognition of the risk factors for adverse outcomes could further assist in patient care and the design of interventional studies that address the severe and widespread problem that is carbapenem resistance.

Fungal Infections in the ICU during the COVID-19 Pandemic in Mexico.

Background: Invasive Fungal Infections (IFI) are emergent complications of COVID-19. In this study, we aim to describe the prevalence, related factors, and outcomes of IFI in critical COVID-19 patients. Methods: We conducted a nested case-control study of all COVID-19 patients in the intensive care unit (ICU) who developed any IFI and matched age and sex controls for comparison (1:1) to evaluate IFI-related factors. Descriptive and comparative analyses were made, and the risk factors for IFI were compared versus controls. Results: We found an overall IFI prevalence of 9.3% in COVID-19 patients in the ICU, 5.6% in COVID-19-associated pulmonary aspergillosis (CAPA), and 2.5% in invasive candidiasis (IC). IFI patients had higher SOFA scores, increased frequency of vasopressor use, myocardial injury, and more empirical antibiotic use. CAPA was classified as possible in 68% and 32% as probable by ECMM/ISHAM consensus criteria, and 57.5% of mortality was found. Candidemia was more frequent for C. parapsilosis Fluconazole resistant outbreak early in the pandemic, with a mortality of 28%. Factors related to IFI in multivariable analysis were SOFA score > 2 (aOR 5.1, 95% CI 1.5-16.8, p = 0.007) and empiric antibiotics for COVID-19 (aOR 30, 95% CI 10.2-87.6, p = <0.01). Conclusions: We found a 9.3% prevalence of IFIs in critically ill patients with COVID-19 in a single center in Mexico; factors related to IFI were associated with higher SOFA scores and empiric antibiotic use for COVID-19. CAPA is the most frequent type of IFI. We did not find a mortality difference.

Histoplasma capsulatum prosthetic joint infection.

Immunocompromised patients are at risk of opportunistic infections. This is a 67-year-old woman with systemic sclerosis and knee osteoarthritis who underwent left total knee arthroplasty in 2009. In 2018 she underwent surgery for presumed aseptic loosening. Inflammation and purulent fluid were found; implant was removed and replaced with a static spacer. Three weeks later, H. capsulatum was isolated. She was successfully treated with itraconazole for 18 months; cultures on revision spacer replacement surgery were negative.

Predictors of Poor Outcomes in Young Non-Comorbid Patients with COVID-19.

Background: Prognostic factors in previously healthy young patients with COVID-19 remained understudied. Objectives: The objective of the study was to identify factors associated with in-hospital death or need for invasive mechanical ventilation (IMV) in young (aged ≤ 65 years) and previously healthy patients with COVID-19. Methods: We conducted a prospective cohort study that included patients admitted with COVID-19. The primary outcome was in-hospital death/need for IMV. Secondary outcomes included need for IMV during follow-up, days on IMV, length of stay (LOS), hospital-acquired pneumonia/ventilator-associated pneumonia (HAP/VAP), and pulmonary embolism (PE). Bivariate and multivariate analyses were performed. Results: Among 92 patients, primary outcome occurred in 16 (17%), death in 12 (13%), need for IMV in 16 (17%), HAP/VAP in 7 (8%), and PE in 2 (2%). Median LOS and IMV duration were 7 and 12 days, respectively. Independent associations were found between the primary outcome and male sex (Adjusted odds ratio [aOR] 7.1, 95%CI 1.1-46.0, p < 0.05), D-dimer levels > 1000ng/mL (aOR 9.0, 95%CI 1.6-49.1, p < 0.05), and RT-PCR Ct-value ≤ 24 on initial swab samples (aOR 14.3, 95%CI 2.0-101.5, p < 0.01). Conclusions: In young and non-comorbid COVID-19 patients, male sex, higher levels of D-dimer, and low SARS-CoV-2 RT-PCR Ct-value on an initial nasopharyngeal swab were independently associated with increased in-hospital mortality or need for IMV. (Rev Invest Clin. 2022;74(5):268-75).

Prevention of COVID-19 superspreading events in buses boarded by presymptomatic cases.

INTRODUCTION: COVID-19 superspreader events have occurred when symptomatic individuals without wearing face masks boarded buses. OBJECTIVE: To report the risk of superspreader events when presymptomatic individuals boarded buses to-gether with unvaccinated passengers, but with non-pharmacological preventive interventions being maintained. METHODS: Prospec-tive study of health personnel transported in buses to a COVID-19 vaccination center for two weeks. Open windows, correct use of face masks and exclusion of symptomatic individuals were mandatory. Prospective surveillance identified workers with COVID-19 within 14 days after vaccination. Each asymptomatic passenger of buses where cases were identified was monitored for a similar time period. Voluntary screening results were available for workers who were tested in the month before or after vaccination. RESULTS: 1,879 workers boarded 65 buses. On-board time ranged from three to eight hours. Twenty-nine cases of COVID-19 and four asymptomatic cases were identified among 613 passengers of 21 buses. Median time between vaccina-tion and COVID-19 symptoms onset was six days. One case of suspected transmission on a bus was identi-fied. CONCLUSIONS: Strict nonpharmacological preventive interventions substantially reduced the risk of COVID-19 super-spreader events in buses boarded by presymptomatic individuals.

ANTECEDENTES: Ha ocurrido superpropagación de COVID-19 cuando individuos sintomáticos sin uso de cubrebocas abordaron autobuses. OBJETIVO: Reportar el riesgo de superpropagación cuando individuos presintomáticos abordaron autobuses junto con pasajeros no vacunados pero se mantuvieron intervenciones preventivas no farmacológicas. MATERIAL Y MÉTODOS: Estudio prospec­tivo de personal de salud transportado durante dos semanas en autobuses a un centro de vacunación contra COVID-19. Fue obligatorio llevar ventanas abiertas, uso correcto de cubrebocas y exclusión de personas con síntomas. La vigilancia prospectiva identificó a trabajadores con COVID-19 los 14 días siguientes a la vacunación. Cada pasajero asintomático de autobuses donde se detectaron casos fue vigilado durante un periodo de tiempo similar. Los resultados de tamizaje voluntario estuvieron disponibles para los trabajadores que se realizaron prueba el mes previo o el siguiente a la vacunación. RESULTADOS: 1879 trabajadores abordaron 65 autobuses. El tiempo a bordo varió de tres a ocho horas. Veintinueve casos de COVID-19 y 4 casos asintomáticos fueron identificados entre 613 pasajeros de 21 autobuses. La mediana de tiempo entre la vacunación y el inicio de síntomas en casos de COVID-19 fue de seis días. Fue identificado un caso de transmisión sospechada en autobús. CONCLUSIONES: Las intervenciones preventivas no farmacológicas estrictas redujeron sustancialmente el riesgo de superpropagación de COVID-19 en autobuses ocupados por individuos presintomáticos.

Early Outpatient Treatment With Remdesivir in Patients at High Risk for Severe COVID-19: A Prospective Cohort Study.

Background: Early treatment of coronavirus disease 2019 (COVID-19) with remdesivir in high-risk patients, including those with immunosuppression of different causes, has not been evaluated. The objective of this study was to assess the clinical effectiveness of early remdesivir treatment among patients with mild to moderate COVID-19 at high risk of progression. Methods: This prospective cohort comparative study was conducted in a tertiary referral center in Mexico City. Patients with mild to moderate COVID-19 at high risk for progression were treated with an ambulatory 3-day course of remdesivir. The primary efficacy composite outcome was hospitalization or death at 28 days after symptom onset. A Cox proportional hazards regression model was used to identify associations with the primary outcome. Results: From December 1, 2021, to April 30, 2022, a total of 196 high-risk patients were diagnosed with COVID-19, of whom 126 were included in this study (43%, 54/126, received remdesivir; 57%, 72/126, did not receive remdesivir). Baseline clinical characteristics were similar between groups; autoimmune diseases (39/126), solid organ transplant (31/126), and malignant neoplasms (24/126) were the most common immunocompromising conditions. Diabetes mellitus was strongly associated with the primary outcome in both groups. Prior severe acute respiratory syndrome coronavirus 2 infection or vaccination was not independently associated with COVID-19 progression. Treatment with remdesivir significantly reduced the odds of hospitalization or death (adjusted hazard ratio, 0.16; 95% CI, 0.06-0.44; P < .01). Conclusions: Early outpatient treatment with remdesivir significantly reduces hospitalization or death by 84% in high-risk, majority immunosuppressed patients with Omicron variant COVID-19.

HIV-positive patients presenting with peripheral blood cytopenias: is bone marrow assessment a priority?

ABSTRACT Introduction: Hematologic abnormalities are frequent among persons living with HIV (PLWH). The bone marrow aspirate (BMA) and biopsy (BMB) are commonly performed in the diagnostic approach of patients with unexplained cytopenias. Changes in antiretrovirals, supportive therapy and increased life expectancy have modified the distribution and etiology of cytopenias, questioning their use. Our aim was to analyze the diagnostic yield of BMA, BMB and marrow cultures for the evaluation of cytopenias in PLWH. Methods: This was a retrospective cohort of ≥ 18-year-old PLWH undergoing bone marrow assessment (MA) for the evaluation of cytopenias between January 2002 and December 2015. Results: A total of 236 cytopenic events were analyzed, 47.9% being PLWH who had a longstanding diagnosis (≥ 1 year). Adherence to antiretrovirals was 63.5%. Anemia was seen in 91.9% and pancytopenia in 39%. Common presentations included fever (52.1%), weight loss (42.8%) and adenopathies (28.8%). Median days from detection to MA was 5 (0 - 63 days). Most common etiologies were non-HIV infectious diseases (31.4%) and benign/malignant hematologic diseases (26.3%). The diagnostic yield was 16.1% for BMA, 20.3% for BMB, 30.5% for both and 35.6% when cultures were added. Patients most likely to have conclusive MA were those with moderate/severe thrombocytopenia (p = 0.007). Fever, splenomegaly, and low CD4+ counts were associated with infectious etiologies, while hematologic diagnoses were related to the presence of adenopathies. Conclusion: As a minimally invasive intervention, the MA has a high yield for identifying the etiology of cytopenic events in PLWH, being conclusive in one in three patients. Early performance could lead to prompt diagnosis and timely therapy initiation.

Predictors of poor outcomes in young non-comorbid patients with COVID-19

ABSTRACT Background: Prognostic factors in previously healthy young patients with COVID-19 remained understudied. Objective: The objective of the study was to identify factors associated with in-hospital death or need for invasive mechanical ventilation (IMV) in young (aged ≤ 65 years) and previously healthy patients with COVID-19. Methods: We conducted a prospective cohort study that included patients admitted with COVID-19. The primary outcome was in-hospital death/need for IMV. Secondary outcomes included need for IMV during follow-up, days on IMV, length of stay (LOS), hospital-acquired pneumonia/ventilator-associated pneumonia (HAP/VAP), and pulmonary embolism (PE). Bivariate and multivariate analyses were performed. Results: Among 92 patients, primary outcome occurred in 16 (17%), death in 12 (13%), need for IMV in 16 (17%), HAP/VAP in 7 (8%), and PE in 2 (2%). Median LOS and IMV duration were 7 and 12 days, respectively. Independent associations were found between the primary outcome and male sex (Adjusted odds ratio [aOR] 7.1, 95%CI 1.1-46.0, p < 0.05), D-dimer levels > 1000ng/mL (aOR 9.0, 95%CI 1.6-49.1, p < 0.05), and RT-PCR Ct-value ≤ 24 on initial swab samples (aOR 14.3, 95%CI 2.0-101.5, p < 0.01). Conclusions: In young and non-comorbid COVID-19 patients, male sex, higher levels of D-dimer, and low SARS-CoV-2 RT-PCR Ct-value on an initial nasopharyngeal swab were independently associated with increased in-hospital mortality or need for IMV.

Significant Rise in SARS-CoV-2 Reinfection Rate in Vaccinated Hospital Workers during the Omicron Wave: A Prospective Cohort Study.

Background: Relatively low SARS-CoV-2 reinfection rates have been reported in vaccinated individuals, but updates considering the Omicron variant are lacking. Objectives: The objective of the study was to provide a current estimate of the SARS-CoV-2 reinfection rate in a highly immunized population. Methods: A prospective cohort of Mexican hospital workers was followed (March 2020-February 2022). Reinfection was defined as the occurrence of two or more episodes of COVID-19 separated by a period of ≥ 90 days without symptoms. The reinfection rate was calculated as the number of reinfection episodes per 100,000 persons per day. Results: A total of 3732 medical consultations were provided to 2700 workers, of whom 1388 (51.4%) were confirmed COVID-19 cases. A total of 73 reinfection cases were identified, of whom 71 (97.3%) had completed their primary vaccination series and 22 (30.1%) had had a booster dose before the second episode. The overall reinfection rate was 23.1 per 100,000 persons per day (as compared to a rate of 1.9 per 100,000 persons per day before the Omicron wave). Conclusions: The SARS-CoV-2 reinfection rate rose significantly during the Omicron wave despite a high primary vaccination coverage rate. Almost one-third of reinfected workers had a vaccine booster ≥ 14 days before the last COVID-19 episode.

Prevención de eventos de superpropagación de COVID-19 en autobuses que transportaron pacientes presintomáticos / Prevention of COVID-19 superspreader events in buses boarded by presymptomatic patients

Resumen Introducción: Ha ocurrido superpropagación de COVID-19 cuando individuos sintomáticos sin uso de cubrebocas abordaron autobuses. Objetivo: Reportar el riesgo de superpropagación cuando individuos presintomáticos abordaron autobuses junto con pasajeros no vacunados, pero se mantuvieron intervenciones preventivas no farmacológicas. Métodos: Estudio prospectivo de personal de salud transportado durante dos semanas en autobuses a un centro de vacunación contra COVID-19. Fue obligatorio llevar ventanas abiertas, uso correcto de cubrebocas y exclusión de personas con síntomas. La vigilancia prospectiva identificó a trabajadores con COVID-19 los 14 días siguientes a la vacunación. Cada pasajero asintomático de autobuses donde se detectaron casos fue vigilado durante un periodo similar. Los resultados de tamizaje voluntario estuvieron disponibles para los trabajadores que se realizaron prueba el mes previo o el siguiente a la vacunación. Resultados: 1879 trabajadores abordaron 65 autobuses. El tiempo a bordo varió de tres a ocho horas. Veintinueve casos de COVID-19 y cuatro casos asintomáticos fueron identificados entre 613 pasajeros de 21 autobuses. La mediana de tiempo entre la vacunación y el inicio de síntomas de COVID-19 fue de seis días. Fue identificado un caso de transmisión sospechada en autobús. Conclusiones: Las intervenciones preventivas no farmacológicas estrictas redujeron sustancialmente el riesgo de superpropagación de COVID-19 en autobuses ocupados por individuos presintomáticos.

Abstract Introduction: COVID-19 superspreader events have occurred when symptomatic individuals without wearing face masks boarded buses. Objective: To report the risk of superspreader events when presymptomatic individuals boarded buses together with unvaccinated passengers, but with non-pharmacological preventive interventions being maintained. Methods: Prospective study of health personnel transported in buses to a COVID-19 vaccination center for two weeks. Open windows, correct use of face masks and exclusion of symptomatic individuals were mandatory. Prospective surveillance identified workers with COVID-19 within 14 days after vaccination. Each asymptomatic passenger of buses where cases were identified was monitored for a similar time period. Voluntary screening results were available for workers who were tested in the month before or after vaccination. Results: 1,879 workers boarded 65 buses. On-board time ranged from three to eight hours. Twenty-nine cases of COVID-19 and four asymptomatic cases were identified among 613 passengers of 21 buses. Median time between vaccination and COVID-19 symptoms onset was six days. One case of suspected transmission on a bus was identified. Conclusions: Strict nonpharmacological preventive interventions substantially reduced the risk of COVID-19 superspreader events in buses boarded by presymptomatic individuals.

Significant Rise in SARS-CoV-2 Reinfection Rate in Vaccinated Hospital Workers during the Omicron Wave: A Prospective Cohort Study

ABSTRACT Background: Relatively low SARS-CoV-2 reinfection rates have been reported in vaccinated individuals, but updates considering the Omicron variant are lacking. Objective: The objective of the study was to provide a current estimate of the SARS-CoV-2 reinfection rate in a highly immunized population. Methods: A prospective cohort of Mexican hospital workers was followed (March 2020-February 2022). Reinfection was defined as the occurrence of two or more episodes of COVID-19 separated by a period of ≥ 90 days without symptoms. The reinfection rate was calculated as the number of reinfection episodes per 100,000 persons per day. Results: A total of 3732 medical consultations were provided to 2700 workers, of whom 1388 (51.4%) were confirmed COVID-19 cases. A total of 73 reinfection cases were identified, of whom 71 (97.3%) had completed their primary vaccination series and 22 (30.1%) had had a booster dose before the second episode. The overall reinfection rate was 23.1 per 100,000 persons per day (as compared to a rate of 1.9 per 100,000 persons per day before the Omicron wave). Conclusions: The SARS-CoV-2 reinfection rate rose significantly during the Omicron wave despite a high primary vaccination coverage rate. Almost one-third of reinfected workers had a vaccine booster ≥ 14 days before the last COVID-19 episode.