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.

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.

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.

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.