Clinical Phenotype of Respiratory Syncytial Virus Bronchiolitis before and during the Coronavirus Disease 2019 Pandemic

Risk Factors for Severe Disease Among Children Hospitalized With Respiratory Syncytial Virus

Importance

A resurgence of respiratory syncytial virus (RSV)-associated acute respiratory tract infection (ARI) was observed in 2022 and 2023 after the COVID-19 pandemic. Changes in the demographic characteristics, disease severity, and outcomes of patients were observed, which could impact the identification of risk groups for interventions aimed at reducing the severity of RSV disease.

Objectives

To identify factors associated with severe clinical outcomes among children hospitalized with RSV-associated ARIs in 2022 and 2023.

Design, Setting, and Participants

This observational cohort study, conducted at 2 large, Canadian, tertiary-level pediatric hospitals, comprised all 709 cases of RSV-associated ARI among children younger than 18 years who were admitted to the hospital or intensive care unit (ICU) from July 1, 2022, to June 30, 2023.

Exposure

Diagnosis of RSV-associated ARI.

Main Outcomes and Measures

The primary outcome of severe disease was defined as requiring noninvasive or invasive ventilation or death. Risk factors for severe disease and ICU admission (secondary outcome) were assessed using multivariable Poisson regression, and results were reported as adjusted risk ratios (ARRs) with 95% CIs, with age-stratified models (<2 years and ≥2 years).

Results

A total of 709 cases (median age, 13.1 months [IQR, 2.0-36.6 months]; 442 boys [62.3%]) were admitted with RSV-associated ARI; 452 (63.8%) were younger than 2 years, and 257 (36.2%) were aged 2 years or older. Severe disease was documented for 204 cases (28.8%). Patients with severe disease were younger than those with nonsevere disease (median age, 2.6 months [IQR, 1.3-16.0 months] vs 18.6 months [IQR, 4.5-39.1 months]; P < .001). Pulmonary disease and use of home oxygen (ARR, 2.47 [95% CI, 1.30-4.68]) and neurologic, neuromuscular, and developmental conditions (ARR, 1.89 [95% CI, 1.03-3.49]) were associated with severe disease among children aged 2 years or older. Among children younger than 2 years, age younger than 3 months (ARR, 2.34 [95% CI, 1.43-3.84]), age 3 to less than 6 months (ARR, 2.79 [95% CI, 1.65-4.70]), and prematurity (ARR, 1.40 [95% CI, 1.03-1.89]) were associated with severe disease.

Conclusions and Relevance

In this cohort study of children hospitalized with RSV in 2022 and 2023, severe RSV disease was more likely among those aged 2 years or older with pulmonary and neurologic, neuromuscular, or developmental conditions. For children younger than 2 years, age younger than 6 months and prematurity were the main risk factors. These findings support prevention strategies for all younger children, including premature infants, with potential benefit for children aged 2 years or older in specific high-risk groups.

Inconsistent Increase in Age at Respiratory Syncytial Virus Hospitalization of Children Aged <2 Years During the Severe Acute Respiratory Syndrome Coronavirus 2 Pandemic: A Retrospective Multicenter Study in 4 European Countries

BACKGROUND

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic disrupted respiratory syncytial virus (RSV) seasonality. To optimize the use and evaluation of RSV infant immunization strategies, monitoring changes in RSV epidemiology is essential.

METHODS

Hospitalizations for acute respiratory infections (ARIs) and RSV-coded ARI in children <2 years were extracted in 4 European hospitals, according to predefined case definitions (International Classification of Diseases, Tenth Revision codes). Prepandemic RSV seasons (2017-2018 to 2019-2020) were compared to 2021-2022 and 2022-2023.

RESULTS

In 2021-2022 and 2022-2023, the peak number of RSV hospitalizations was higher than prepandemic peaks after short periods of RSV circulation, and lower than prepandemic peaks after long periods of RSV circulation. A greater proportion of RSV hospitalizations occurred in children 1 to <2 years in 2021-2022 in the Netherlands (18% vs 9%, P = .04). No increase in age was observed elsewhere. High-risk children represented a greater proportion of RSV hospitalizations during the pandemic. The proportion of pediatric intensive care unit admissions did not increase.

CONCLUSIONS

A decrease in population immunity has been linked to older age at RSV hospitalization. We did not observe an increase in age in 3 of the 4 participating countries. Broad age categories may have prevented detecting an age shift. Monitoring RSV epidemiology is essential as Europe implements RSV immunization.

"Comparison between high-flow nasal cannula (HFNC) therapy and noninvasive ventilation (NIV) in children with acute respiratory failure by bronchiolitis: a randomized controlled trial"

BACKGROUND

The objective of this study was to compare HFNC therapy to noninvasive ventilation (NIV/BiPAP) in children with bronchiolitis who developed respiratory failure. We hypothesized that HFNC therapy would not be inferior to NIV.

METHODS

This was a noninferiority open-label randomized single-center clinical trial conducted at a tertiary Brazilian hospital. Children under 2 years of age with no chronic conditions admitted for bronchiolitis that progressed to mild to moderate respiratory distress (Wood-Downes-Férres score < 8) were randomized to either the HFNC group or NIV (BiPAP) group through sealed envelopes. Vital signs, FiO2, Wood-Downes-Férres score and HFNC/NIV parameters were recorded up to 96 h after therapy initiation. Children who developed respiratory failure despite receiving initial therapy were intubated. Crossover was not allowed. The primary outcome analyzed was invasive mechanical ventilation requirement. The secondary outcomes were sedation usage, invasive mechanical ventilation duration, the PICU LOS, the hospital LOS, and mortality rate.

RESULTS

A total of 126 patients were allocated to the NIV group (132 randomized and 6 excluded), and 126 were allocated to the HFNC group (136 randomized and 10 excluded). The median age was 2.5 (1-6) months in the NIV group and 3 (2-7) months in the HFNC group (p = 0,07). RSV was the most common virus isolated in both groups (72% vs. 71.4%, NIV and HFNC, respectively). Thirty-seven patients were intubated in the NIV group and 29 were intubated in the HFNC group (29% vs. 23%, p = 0.25). According to the Farrington-Manning test, with a noninferiority margin of 15%, the difference was 6.3% in favor of HFNC therapy (95% confidence interval: -4.5 to 17.1%, p < 0.0001). There was no significant difference in the PICU LOS or sedation duration. Sedation requirement, hospital LOS and invasive mechanical ventilation duration were lower in the HFNC group.

CONCLUSION

HFNC therapy is noninferior to NIV in infants admitted with mild to moderate respiratory distress caused by bronchiolitis that progresses to respiratory failure.

TRIAL REGISTRATION NUMBERS

U1111-1262-1740; RBR-104z966s. Registered 03/01/2023 (retrospectively registered). ReBEC: https://ensaiosclinicos.gov.br/rg/RBR-104z966s .

New Insights on Respiratory Syncytial Virus Prevention

Respiratory syncytial virus (RSV) is a well-known infant pathogen transmitted mainly by droplets. It is a leading cause of upper respiratory tract infections in children, usually with a mild course of illness. RSV has also been a threat to older people, especially those with underlying medical conditions. For a long time, prevention was limited to passive immunoprophylaxis with palivizumab for high-risk infants. There was a strong need to find other treatment or prevention methods against RSV infections. In addition, after the coronavirus disease 2019 (COVID-19) pandemic, some significant changes in RSV epidemiology have been observed. Researchers noticed the shift in RSV seasonality and age distribution and the increased number of cases in older infants and adults. All of these made the need to find other medical options even stronger. Fortunately, two protein-based vaccines against RSV have successfully passed all phases of clinical trials and have been approved for use by adults and older people. One of them is also approved for infants from birth to 6 months of age (after maternal immunisation during pregnancy) and for pregnant women between 24 and 36 weeks of pregnancy. Also, a new passive immunisation option named nirsevimab (a highly potent monoclonal antibody with a long half-life) is now available for the paediatric group. In this review, we will discuss the previous and current RSV prevention methods in the light of structural discoveries of RSV antigens.

Why has the epidemiology of RSV changed during the COVID-19 pandemic?

The coronavirus disease 2019 (COVID-19) pandemic has drastically perturbed the epidemiology of Respiratory Syncytial Virus (RSV) respiratory tract infections in children. The reasons for this are not clear. In this article, we review the current literature and critically discuss the different theories to explain why the epidemiology of RSV has changed during the COVID-19 pandemic. Proposed mechanisms include decreased viral immunity in vulnerable age groups caused by the prolonged lack of RSV circulation early in the pandemic, potential Severe Acute Respiratory Syndrome Corona Virus 2 (SARS-CoV-2)-induced immune dysregulation, viral interactions between SARS-CoV-2 and RSV, and modifications in health-seeking behaviors as well as heath systems factors. Research in viral genomics and phylogeny, and more robust immunology research is needed to guide RSV prevention and health care resource planning.