Risk factors for severe disease in pediatric respiratory syncytial virus infections.

OBJECTIVES: To assess factors associated with the risk of severe disease in children aged 5 years or younger with laboratory-confirmed respiratory syncytial virus (RSV) infection. STUDY DESIGN: We conducted a nationwide retrospective cohort study in Mexico. METHODS: Eligible participants included children aged 5 years or younger with laboratory-confirmed RSV infection January 1, 2023, and May 15, 2024. We collected relevant clinical and epidemiological data. Risk ratios (RR) and 95% confidence intervals (CI) were employed to identify factors associated with the risk of severe disease, characterized by clinical and radiographic evidence of bronchiolitis or pneumonia requiring hospital admission. RESULTS: Data from 2022 children were analyzed and the overall risk of severe disease was 21.0% (n = 424/2022). In multiple generalized linear regression analysis, a personal history of immunosuppression (due to any cause) showed a protective effect (RR = 0.14, 95% CI 0.05-0.42, P = 0.001) against severe RSV disease, while an increased risk was documented for each additional day elapsed between the date of symptom onset and the date of seeking healthcare RR = 1.06, 95% CI 1.02-1.10, P = 0.004). CONCLUSION: These findings provide insights into risk stratification and suggest specific directions for future research. This information informs the development of targeted intervention strategies to mitigate the impact of RSV infections in this vulnerable population.

The burden of COVID-19 in Latin American and Caribbean countries: an analysis based on the Global Burden of Disease Study 2021.

OBJECTIVES: The coronavirus disease 2019 (COVID-19) pandemic has had a profound impact on the countries of Latin America and the Caribbean. This study aims to summarise key findings from the Global Burden of Disease (GBD) 2021 in the region. We also explore disparities in burden rates and the relationship with the Socio-demographic Index (SDI). STUDY DESIGN: A cross-sectional analysis of GBD 2021 results was conducted. METHODS: We obtained the disability-adjusted life years (DALYs) due to COVID-19 for 20 countries, analysing number- and age-adjusted rates. Spearman's correlation (rho) and 95% confidence intervals (CIs) assessed the SDI-DALY rates relationship. RESULTS: COVID-19 was the leading cause disease burden in the region, with 20,437,321 DALYs in 2020 and 31,525,824 in 2021. Premature mortality (years of life lost) accounted for over 95%. Disparities existed across sexes, age groups, and countries, with Bolivia and Peru having the highest rates. A significant 2021 correlation was found (rho = -0.55, 95% CI: -0.90 to 0.19; P = 0.013) but not in 2020 (rho = -0.40, 95% CI: -0.75 to 0.05; P = 0.078). CONCLUSIONS: COVID-19 posed a significant burden in Latin America and the Caribbean, emphasising the need for targeted interventions, especially in socioeconomically disadvantaged regions.

Assessing the asthma-related burden of disease in Latin American and Caribbean countries: a sociodemographic perspective.

OBJECTIVE: This study aimed to characterize the burden of asthma-related issues in Latin American and Caribbean countries from 1990 to 2019 and to assess their relationship with the sociodemographic index (SDI). STUDY DESIGN: A cross-sectional analysis with an ecological approach was conducted. METHODS: The disability-adjusted life years (DALYs) and the SDI data were obtained from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019. Linear regression models were used to evaluate the relationship of interest. RESULTS: During the study period, a total of 41.7 million DALYs were accounted, with the highest rates observed in children aged under 5 years (651, uncertainty interval [UI]: 369 to 1037 per 100,000) and females (342, UI: 241 to 471 per 100,000). In the multiple regression model based on data from 2019, a significant negative association was observed between the log-transformed DALY rates and the SDI. Specifically, for each unit increase in the SDI, asthma-related DALY rates decreased by an average of 0.97 % (95 % confidence interval: 0.48-1.00 %). CONCLUSIONS: This study highlights heterogeneous age, gender, and country-related variations in asthma rates across Latin American and Caribbean countries and emphasizes the influence of sociodemographic factors on its burden.

Evaluating the performance of WHO and CDC case definitions for influenza-like illness in diagnosing influenza during the 2022-2023 flu season in Mexico.

OBJECTIVE: This study aimed to evaluate the performance of the World Health Organization (WHO) and Centers for Disease Control and Prevention (CDC) case definitions for influenza-like illness (ILI) in diagnosing influenza during the 2022-2023 flu season in Mexico. STUDY DESIGN: We conducted a cross-sectional analysis of national epidemiological surveillance data in Mexico, focusing on respiratory viral pathogens. METHODS: We analyzed data from 6027 non-hospitalized patients between 5 and 65 years old who underwent molecular testing for respiratory viral pathogens. The performance of both case definitions was evaluated in terms of sensitivity, specificity, and the area under the receiver operating characteristic (AUROC) curve. RESULTS: Overall, the diagnostic accuracy of the evaluated ILI definitions in identifying influenza patients was low, particularly among older patients. When compared to the CDC, the WHO definition had a lower sensitivity but a higher specificity, resulting in a higher AUROC (P = 0.031) for the WHO criteria. CONCLUSIONS: Our findings suggest that the WHO and CDC ILI case definitions have limited accuracy for diagnosing influenza in non-hospitalized patients and highlight the need for more specific diagnostic tools to improve the detection of influenza cases during the flu season.

Respiratory syncytial virus infection: survival experience in a cohort of children inpatients.

OBJECTIVE: The objective of this study was to assess the survival experience of children hospitalized with laboratory-confirmed respiratory syncytial virus (RSV) infection due to bronchiolitis. STUDY DESIGN: This was a nationwide retrospective cohort study conducted in Mexico. METHODS: We analyzed data from 436 children aged 5 years and younger, with symptom onset between August 2021 and November 2022. The Kaplan-Meier method was used to compute survivor functions and their 95% confidence intervals (CI). RESULTS: High survival rates were observed, particularly within the first three weeks of hospital admission. The 3-day survival rate was 99.8% (CI 98.4-99.9%), which decreased to 98.9% (CI 96.5-99.7%), 97.5% (CI 91.9-99.3%), 86.7% (CI 48.2-97.2%), and 69.4% (CI 24.2-91.0%) on days 7, 14, 21, and 28 of hospital stay, respectively. We documented a total of 5 fatal outcomes, resulting in a mortality rate of 2.1 (95% CI 0.9-5.1) per 1,000 person-days. CONCLUSIONS: Our study analyzed a large cohort of pediatric patients with bronchiolitis caused by RSV infection, providing valuable insights into the in-hospital progression of this disease.

Comparing the survival of adult inpatients with COVID-19 during the wild-type, Delta, and Omicron emergence.

OBJECTIVE: This study aimed to compare the survival experience of adult inpatients with laboratory-confirmed COVID-19 during the first three waves (wild type, Delta, and Omicron) of the pandemic in Mexico. STUDY DESIGN: A retrospective and nationwide study was conducted. METHODS: Data from 229,311 participants were analyzed using the Kaplan-Meier method, and estimates per each pandemic wave were obtained. A multivariate Cox proportional hazard regression model was fitted, and hazard ratios (HRs) and 95% confidence intervals (CIs) were computed. RESULTS: The overall mortality rate was 49.1 per 1000 person-days. Heterogeneous survival rates were observed during the analyzed emergences (log-rank test, P < 0.001), and the lowest survival functions were computed during the Omicron variant dominance. In multiple analyses and after adjusting by host characteristics and COVID-19 vaccination status, cases occurring during the Delta (vs wild type: HR = 1.03, 95% CI 1.01-1.05) and Omicron emergence were at increased risk for a fatal in-hospital outcome (HR = 1.17, 95% CI 1.13-1.22). CONCLUSIONS: Our results suggest variant-related differences in the survival rates of hospitalized patients with laboratory-positive COVID-19. When compared with the wild-type virus, lower rates were observed during the Delta and Omicron emergence.

First-generation BNT162b2 and AZD1222 vaccines protect from COVID-19 pneumonia during the Omicron variant emergence.

OBJECTIVE: This study aimed to identify factors predicting pneumonia in adults with coronavirus disease 2019 (COVID-19) during the Omicron variant (B.1.1.529) emergence. We also evaluated, in fully vaccinated (BNT162b2 or AZD1222) individuals, if the time (<6 or ≥6 months) elapsed since the last shot was received was associated with the risk of severe illness. STUDY DESIGN: A retrospective cohort study was conducted in Mexico. METHODS: Data from 409,493 were analyzed, and risk ratios (RRs) and 95% confidence intervals (CIs) were computed through generalized linear models. RESULTS: We documented a total of 3513 COVID-19 pneumonia cases (69.5 per 100,000 person-days). In multiple analyses, a protective effect was observed in vaccinated adults (RR = 0.996, 95% CI 0.995-0.997). Male gender, increasing age, and smoking were associated with a greater risk of pneumonia. Individuals with chronic comorbidities (pulmonary obstructive disease, type 2 diabetes mellitus, arterial hypertension, kidney disease, and immunosuppression) were also at higher risk. Among fully vaccinated subjects (n = 166,869), those who had received the last shot at 6 more months were at increased risk for developing pneumonia (RR = 1.002, 95% CI 1.001-1.003). CONCLUSIONS: Our results suggest that the first-generation BNT162b2 and AZD1222 vaccines reduce the risk of COVID-19 pneumonia during the Omicron emergence. We also found that adults with longer interval from the administration of the second shot to illness onset were at increased risk of severe manifestations.

Decreased risk of COVID-19 pneumonia in children and adolescents during the Delta variant emergence.

OBJECTIVES: This study aimed to evaluate factors associated with the risk of COVID-19 pneumonia in children (aged <10 years) and adolescents (aged 10-19 years) before (March 2020-April 2021) and during (May-July 2021) the Delta (B.1.617.2) variant emergence. STUDY DESIGN: A retrospective and nationwide cohort study was conducted in Mexico. METHODS: Data from 26,961 laboratory-confirmed cases of COVID-19 were analyzed. Risk ratios (RRs) and 95% confidence intervals (CIs) were used to evaluate the association of the evaluated exposures with the risk of COVID-19 pneumonia. RESULTS: The overall incidence rate of pneumonia was 23.0 per 10,000 person-days, and it was lower during the Delta variant emergence (30.3 vs. 9.4 person-days, p < 0.001). In multiple analysis, a decreased risk of pneumonia was observed among those cases occurring in May 2021 or later (vs. March 2020-April 2021, RR = 0.98, 95% CI 0.97-0.99) and among older patients (RRper year = 0.998, 95% CI 0.996-0.998). Other comorbidities (namely, obesity, chronic kidney disease, diabetes mellitus, immunosuppression, or malignant tumors) were associated with an increased risk of severe COVID-19 manifestations. CONCLUSIONS: Our findings suggest that during the Delta variant emergence, children and adolescent patients were at reduced risk of COVID-19 pneumonia in Mexico. Further research is needed to identify factors determining the observed scenario.

Survival in adult pneumonia inpatients fulfilling suspected COVID-19 criteria and baseline negative RT-qPCR.

OBJECTIVES: The objective of this study was to evaluate the survival experience of suspicion COVID-19 hospitalized patients with pneumonia and negative baseline reverse-transcription quantitative polymerase chain reaction (RT-qPCR) test results. STUDY DESIGN: We conducted a nationwide retrospective cohort study in Mexico. METHODS: Adult pneumonia inpatients fulfilling suspected COVID-19 criteria, and hospital entry from March to August 2020, were enrolled. The Kaplan-Meier method was to use to compare survival estimates among patients with negative RT-qPCR nasopharyngeal or oropharyngeal swabs and those with a baseline positive test. RESULTS: Data from 64,624 individuals fulfilling suspected COVID-19 criteria were analyzed and 1.6% of them had negative RT-qPCR tests. The overall mortality rate was higher among laboratory-positive patients (48.5% vs. 34.2%, P < 0.001) and, at any given threshold, the survival estimates were higher among RT-qPCR-negative pneumonia inpatients. CONCLUSIONS: The pathogenic mechanism of COVID-19 remains poorly understood and suspected cases with pneumonia and negative laboratory results represent a major challenge for healthcare systems. Our findings suggest that RT-qPCR-negative inpatients may have an improved disease prognosis, but the in-hospital mortality was still high among them. However, further research is needed to clarify the clinical and epidemiological implications of our results.

National retrospective cohort study to identify risk factors for in-hospital 30-day lethality in laboratory-confirmed cases of influenza.

OBJECTIVE: To identify factors associated with the risk of death in adolescent and adult inpatients with laboratory-positive (reverse-transcription polymerase chain reaction) influenza in Mexico during consecutive influenza seasons (2018-2020). METHODS: A retrospective cohort study used national surveillance system data, enrolling 3.422 individuals. The association between various risk factors and 30-day in-hospital lethality were evaluated through risk ratios (RRs) and 95% confidence intervals (CIs). RESULTS: The lethality rate was 18.1%. Flu vaccination history (RR=0.56, 95% CI 0.42-0.78), early antiviral drug administration (≤2 days from symptom onset [reference ≥5 days], RR=0.68, 95% CI 0.58-0.81), and a history of asthma (RR=0.66, 95% CI 0.47-0.95) showed protective effects against influenza-attributable death. Mechanical ventilator support produced the highest increase in death risk (RR=3.31, 95% CI 2.89-3.79). Male sex, older age, AH1N1 subtype, and other chronic diseases were also associated with fatal in-hospital influenza-related outcomes. CONCLUSIONS: Our findings highlight the major relevance of promoting immunization in high-risk individuals, together with ensuring early and effective antiviral management in suspected influenza cases.

Predictors of severe symptomatic laboratory-confirmed SARS-CoV-2 reinfection.

OBJECTIVE: The aim of the study was to evaluate factors predicting severe symptomatic laboratory-confirmed (via Reverse transcription polymerase chain reaction, RT-PCR polymerase chain reaction) severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) reinfection. STUDY DESIGN: This is a nationwide retrospective cohort study that was conducted in Mexico. METHODS: Data from 258 reinfection cases (at least 28 days between both episodes onset) were analyzed. We used risk ratios (RRs) and 95% confidence intervals (CIs) to evaluate predictors of severe (dyspnea requiring hospital admission) secondary SARS-CoV-2 infection. RESULTS: The risk of severe disease was 14.7%, and the observed overall fatality rate was 4.3%. Patients with more serious primary disease were more likely to develop severe symptoms (39.5% vs. 5.5%, P < 0.001) during reinfection. In multiple analysis, factors associated with an increased risk of severe symptomatic SARS-CoV-2 reinfection were increasing age (RRper year = 1.007, 95% CI = 1.003-1.010), comorbidities (namely, obesity [RR = 1.12, 95% CI = 1.01-1.24], asthma [RR = 1.26, 95% CI = 1.06-1.50], type 2 diabetes mellitus [RR = 1.22, 95% CI = 1.07-1.38]), and previous severe laboratory-confirmed coronavirus disease 2019 (RR = 1.20, 95% CI = 1.03-1.39). CONCLUSIONS: To the best of our knowledge, this is the first study evaluating disease outcomes in a large set of laboratory-positive cases of symptomatic SARS-CoV-2 reinfection, and factors associated with illness severity were characterized. Our results may contribute to the current knowledge of SARS-CoV-2 pathogenicity and to identify populations at increased risk of a poorer outcome after reinfection.

National retrospective cohort study to identify risk factors for in-hospital 30-day lethality in laboratory-confirmed cases of influenza. / Estudio de cohorte retrospectivo nacional para identificar los factores de riesgo de letalidad por hospitalización durante 30 días en casos de gripe confirmados por laboratorio.

OBJECTIVE: To identify factors associated with the risk of death in adolescent and adult inpatients with laboratory-positive (reverse-transcription polymerase chain reaction) influenza in Mexico during consecutive influenza seasons (2018-2020). PATIENTS AND METHODS: A retrospective cohort study used national surveillance system data, enrolling 3422 individuals. The association between various risk factors and 30-day in-hospital lethality were evaluated through risk ratios (RR) and 95% confidence intervals (CI). RESULTS: The lethality rate was 18.1%. Flu vaccination history (RR = 0.56, 95% CI 0.42-0.78), early antiviral drug administration (≤ two days from symptom onset [reference ≥ 5 days], RR = 0.68, 95% CI 0.58-0.81), and a history of asthma (RR = 0.66, 95% CI 0.47-0.95) showed protective effects against influenza-attributable death. Mechanical ventilator support produced the highest increase in death risk (RR = 3.31, 95% CI 2.89-3.79). Male sex, older age, AH1N1 subtype, and other chronic diseases were also associated with fatal in-hospital influenza-related outcomes. CONCLUSIONS: Our findings highlight the major relevance of promoting immunization in high-risk individuals, together with ensuring early and effective antiviral management in suspected influenza cases.