Respiratory Virus Season Research Articles

Transient increased risk of influenza infection following RSV infection in South Africa: findings from the PHIRST study, South Africa, 2016–2018

BackgroundLarge-scale prevention of respiratory syncytial virus (RSV) infection may have ecological consequences for co-circulating pathogens, including influenza. We assessed if and for how long RSV infection alters the risk for subsequent influenza infection.MethodsWe analysed a prospective longitudinal cohort study conducted in South Africa between 2016 and 2018. For participating households, nasopharyngeal samples were taken twice weekly, irrespective of symptoms, across three respiratory virus seasons, and real-time polymerase chain reaction (PCR) was used to identify infection with RSV and/or influenza. We fitted an individual-level hidden Markov transmission model in order to estimate RSV and influenza infection rates and their interdependence.ResultsOf a total of 122,113 samples collected, 1265 (1.0%) were positive for influenza and 1002 (0.8%) positive for RSV, with 15 (0.01%) samples from 12 individuals positive for both influenza and RSV. We observed a 2.25-fold higher incidence of co-infection than expected if assuming infections were unrelated. We estimated that infection with influenza is 2.13 (95% CI 0.97–4.69) times more likely when already infected with, and for a week following, RSV infection, adjusted for age. This equates to 1.4% of influenza infections that may be attributable to RSV in this population. Due to the local seasonality (RSV season precedes the influenza season), we were unable to estimate changes in RSV infection risk following influenza infection.ConclusionsWe find no evidence to suggest that RSV was associated with a subsequent reduced risk of influenza infection. Instead, we observed an increased risk for influenza infection for a short period after infection. However, the impact on population-level transmission dynamics of this individual-level synergistic effect was not measurable in this setting.

Influenza Antiviral Shortages Reported by State and Territorial Public Health Officials, 2022-2023

This study provides survey results from state and territorial public health preparedness directors regarding antiviral shortages during the 2022-2023 respiratory viral season.

Respiratory virus surveillance in hospitalized children less than two-years of age in Kenema, Sierra Leone during the COVID-19 pandemic (October 2020- October 2021).

Globally, viral pathogens are the leading cause of acute respiratory infection in children under-five years. We aim to describe the epidemiology of viral respiratory pathogens in hospitalized children under-two years of age in Eastern Province of Sierra Leone, during the second year of the SARS-CoV-2 pandemic. We conducted a prospective study of children hospitalized with respiratory symptoms between October 2020 and October 2021. We collected demographic and clinical characteristics and calculated each participant´s respiratory symptom severity. Nose and throat swabs were collected at enrollment. Total nucleic acid was purified and tested for multiple respiratory viruses. Statistical analysis was performed using R version 4.2.0 software. 502 children less than two-years of age were enrolled. 376 (74.9%) had at least one respiratory virus detected. The most common viruses isolated were HRV/EV (28.2%), RSV (19.5%) and PIV (13.1%). Influenza and SARS-CoV-2 were identified in only 9.2% and 3.9% of children, respectively. Viral co-detection was common. Human metapneumovirus and RSV had more than two-fold higher odds of requiring O2 therapy while hospitalized. Viral pathogen prevalence was high (74.9%) in our study population. Despite this, 100% of children received antibiotics, underscoring a need to expand laboratory diagnostic capacity and to revisit clinical guidelines implementation in these children. Continuous surveillance and serologic studies among more diverse age groups, with greater geographic breadth, are needed in Sierra Leone to better characterize the long-term impact of COVID-19 on respiratory virus prevalence and to better characterize the seasonality of respiratory viruses in Sierra Leone.

Clinical features of febrile seizures in children with COVID-19: an observational study from a tertiary care hospital in China.

Febrile seizures are a common neurologic manifestation in children with coronavirus disease 2019 (COVID-19). Compared to seasonal respiratory viruses, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has a pronounced neurological impact, with the result that febrile seizures with COVID-19 may exhibit unique clinical features. We conducted a retrospective study in a tertiary care hospital in China. We collected medical record information on febrile seizures with COVID-19, including demographic characteristics, clinical features, laboratory tests, and disease burden. Subsequently, the data were then analyzed descriptively. A total of 103 children diagnosed with febrile seizures and positive COVID-19 PCR results were included in our study. Among them, 81 (78.6%) were males and 22 (21.4%) were females. The age of onset of febrile seizures ranged from 14 to 57 months, with a mean age of 34.9 ± 6.24 months. Complex febrile seizures were observed in 34 (33%) cases. Antiseizure medications were administered to 24 (23.3%) patients. Laboratory tests showed a white blood cell count of (27.05 ± 8.20) × 103/µl, a neutrophil count of (20.09 ± 5.66) × 103/µl and a lymphocyte count of (6.44 ± 1.86) × 103/µl. A creatine kinase level was significantly elevated, with a mean value of (412.00 ± 158.96) U/L. The mean length of stay was 4.36 days. Twelve patients (11.7%) required intensive care services, but there were no deaths or patients remaining on antiseizure medications after discharge. In the post-epidemic era of COVID-19, pediatric clinicians should be aware of the changing clinical features of febrile seizures associated with COVID-19. The average age of onset has increased, with a higher proportion of males. Length of stay and hospitalization costs did not increase significantly. The prognosis remained favorable, although a small number of children required intensive care services during the acute phase.

Risk factors for severity in seasonal respiratory viral infections and how they guide management in hematopoietic cell transplant recipients.

Seasonal respiratory virus infections (RVIs) often progress to severe diseases in hematopoietic cell transplant (HCT) recipients. This review summarizes the current evidence on risk factors for the severity of RVIs in this high-risk population and provides clinical management. The likelihood of the respiratory viral disease progression depends on the immune status of the host and the type of virus. Conventional host factors, such as the immunodeficiency scoring index and the severe immunodeficiency criteria, have been utilized to estimate the risk of progression to severe disease, including mortality. Recent reports have suggested nonconventional risk factors, such as hyperglycemia, hypoalbuminemia, prior use of antibiotics with broad anaerobic activity, posttransplant cyclophosphamide, and pulmonary impairment after RVIs. Identifying novel and modifiable risk factors is important with the advances of novel therapeutic and preventive interventions for RVIs. Validation of recently identified risk factors for severe RVIs in HCT recipients is required. The development of innovative interventions along with appropriate risk stratification is critical to improve outcomes in this vulnerable population.

Wastewater Surveillance Data as a Complement to Emergency Department Visit Data for Tracking Incidence of Influenza A and Respiratory Syncytial Virus - Wisconsin, August 2022-March 2023.

Wastewater surveillance has been used to assist public health authorities in tracking local transmission of SARS-CoV-2. The usefulness of wastewater surveillance to track community spread of other respiratory pathogens, including influenza virus and respiratory syncytial virus (RSV), is less clear. During the 2022-23 respiratory diseases season, concentrations of influenza A virus and RSV in wastewater samples in three major Wisconsin cities were compared with emergency department (ED) visits associated with these pathogens. In all three cities, higher concentrations of influenza A virus and RSV in wastewater were associated with higher numbers of associated ED visits (Kendall's tau range=0.50-0.63 for influenza-associated illness and 0.30-0.49 for RSV-associated illness). Detections of both influenza A virus and RSV in wastewater often preceded a rise in associated ED visits for each pathogen, and virus material remained detectable in wastewater for up to 3 months after pathogen-specific ED visits declined. These results demonstrate that wastewater surveillance has the potential to complement conventional methods of influenza and RSV surveillance, detecting viral signals earlier and for a longer duration than do clinical data. Continued use of wastewater surveillance as a supplement to established surveillance systems such as ED visits might improve local understanding and response to seasonal respiratory virus outbreaks.

Surveillance of respiratory viruses at health facilities from across Kenya, 2014

Background: Acute respiratory illnesses (ARI) are a major cause of morbidity and mortality globally. With (re)emergence of novel viruses and increased access to childhood bacterial vaccines, viruses have assumed greater importance in the aetiology of ARI. There are now promising candidate vaccines against some of the most common endemic respiratory viruses. Optimal delivery strategies for these vaccines, and the need for interventions against other respiratory viruses, requires geographically diverse data capturing temporal variations in virus circulation. Methods: We leveraged three health facility-based respiratory illness surveillance platforms operating in 11 sites across Kenya. Nasopharyngeal (NP) and/or oropharyngeal (OP) specimens, patient demographic, and clinical characteristics were collected in 2014 from individuals of various ages presenting with respiratory symptoms at the surveillance facilities. Real time multiplex polymerase chain reaction was used to detect rhinoviruses, respiratory syncytial virus (RSV), influenza virus, human coronaviruses (hCoV), and adenoviruses. Results: From 11 sites, 5451 NP/OP specimens were collected and tested from patients. Of these, 40.2% were positive for at least one of the targeted respiratory viruses. The most frequently detected were rhinoviruses (17.0%) and RSV A/B (10.5%), followed by influenza A (6.2%), adenovirus (6.0%) and hCoV (4.2%). RSV was most prevalent among infants aged <12 months old (18.9%), adenovirus among children aged 12–23 months old (11.0%), influenza A among children aged 24–59 months (9.3%), and rhinovirus across all age groups (range, 12.7–19.0%). The overall percent virus positivity varied by surveillance site, health facility type and case definition used in surveillance. Conclusions: We identify rhinoviruses, RSV, and influenza A as the most prevalent respiratory viruses. Higher RSV positivity in inpatient settings compared to outpatient clinics strengthen the case for RSV vaccination. To inform the design and delivery of public health interventions, long-term surveillance is required to establish regional heterogeneities in respiratory virus circulation and seasonality.

Comparative Analysis of Pediatric Hospitalizations during Two Consecutive Influenza and Respiratory Virus Seasons Post-Pandemic.

The COVID-19 pandemic has had a significant impact on the epidemiology of respiratory viruses. Non-pharmaceutical interventions (NPIs) led to a dramatic reduction in respiratory infections. However, the long-term effects on respiratory virus epidemiology remain unclear. We conducted a comparative study on hospitalized pediatric patients with respiratory illness during two seasons: 1 October 2021 to 15 March 2022 and 1 October 2022 to 15 March 2023. We compared the type of virus, mean duration of hospitalization, and disease severity. In the first season, 47.1% of patients (65/138) tested positive for at least one respiratory virus, with respiratory syncytial virus (RSV) being the most frequent (23.2%). In the second season, 82.9% of patients (102/123) tested positive, with RSV and Rhinovirus being the most prevalent (28.38% and 27.03%, respectively). Other viruses, such as Influenza A/B, Metapneumovirus, and Adenovirus, also showed increased prevalence. Disease severity and mean duration of hospitalization were similar between the two seasons. Our study highlights increased prevalence in respiratory viruses, including RSV and Rhinovirus, following the easing of NPIs. The prevalence in respiratory viruses, including RSV and Rhinovirus, increased in the second season compared to the first one. Interestingly, RSV's peak incidence shifted from February to November. The emergence of rhinovirus as the most prevalent respiratory virus during certain months suggests viral competition and dynamic changes in viral circulation. The overall severity of respiratory infections remained relatively stable between the seasons.

The Seasonality of Respiratory Viruses in a Hong Kong Hospital, 2014-2023.

We reviewed the multiplex PCR results of 20,127 respiratory specimens tested in a hospital setting from January 2014 to April 2023. The seasonal oscillation patterns of 17 respiratory viruses were studied. Compared with 2014-2019, a prominent drop in PCR positivity (from 64.46-69.21% to 17.29-29.89%, p < 0.001) and virus diversity was observed during the COVID-19 pandemic, with predominance of rhinovirus/enterovirus, sporadic spikes of parainfluenza viruses 3 and 4, respiratory syncytial virus and SARS-CoV-2, and rare detection of influenza viruses, metapneumovirus, adenovirus and coronaviruses. The suppressed viruses appeared to regain activity from the fourth quarter of 2022 when pandemic interventions had been gradually relaxed in Hong Kong. With the co-circulation of SARS-CoV-2 and seasonal respiratory viruses, surveillance of their activity and an in-depth understanding of the clinical outcomes will provide valuable insights for improved public health measures and reducing disease burden.

The relationship between aeroallergen sensitivity variations and Covid 19 in patients with rhinitis

Objective: There have been studies evaluating the association between AR and COVID-19 infection, but these studies did not evaluate the sensitisation of patients. The objective of this study was to examine the impact of allergen sensitisation on the transmission of viral infections and the progression of the disease. Material and Methods: Rhinitis patients admitted to the Adult Allergy Outpatient Clinic between April and June 2021 were included in the study. Aeroallergen sensitisation and COVID-19 disease status of the patients were evaluated. Results: Data were collected from 260 patients. It was determined that 23.8% (n=62) of the patients had COVID-19 and 17.7% (n=11) had COVID-19 pneumonia. This rate was higher than the incidence of COVID-19 in the general population. The rate of COVID-19 infection was significantly higher in patients with pollen allergy compared to other groups (p=0.049). When the COVID-19 transmission periods of the patients were analysed, it was observed that 55% of them were infected between March and September in accordance with the pollen map. Patients taking steroids (INCS or ICS) did not have an increased risk of COVID infection, and concomitant asthma did not pose an increased risk. Having chronic diseases was found to be a risk factor. Conclusions: This study provides clinical evidence of an increased frequency of infection in AR patients, especially in AR patients with pollen allergy. This result is valuable as it is a data not presented in existing studies. We also think that the risk of COVID-19 increases with pollen exposure. As pollen can suppress antiviral immunity, we recommend that chronic disease groups pay special attention to prevention methods, especially when pollen and respiratory virus seasons overlap.

The Effect of Glasgow Prognostic Score And Systemic Inflammatory Index On Mortality In Patients With Postoperative Pneumonia

The Effect of Glasgow Prognostic Score And Systemic Inflammatory Index On Mortality In Patients With Postoperative Pneumonia

Seasonal respiratory virus trends in pediatric patients during the COVID-19 pandemic in Brazil.

Acute respiratory infections are a constant public health problem causing childhood morbidity and mortality worldwide. Reported cases of major respiratory infections decreased in 2020 after restrictive measures were adopted to contain the COVID-19 pandemic, but there is little data on the impact after these measures were relaxed in the subsequent years. This study conducted molecular analysis to identify rhinovirus, respiratory syncytial virus, influenza A virus, and adenovirus in SARS-CoV-2-negative samples taken from symptomatic pediatric patients during 2021 and 2022 to ascertain the impact of pandemic response measures within the broader epidemiological scenario. The positivity rates found were 28.3% and 50.8%, in 2021 and 2022, respectively, representing a significant increase (1.8 times) in the circulation of non-SARS-CoV-2 viruses after the reduction of non-pharmacological measures to contain the COVID-19 pandemic. Within the positive samples, rhinovirus and respiratory syncytial virus were most frequent (44.4 and 18% in 2021; 44.5 and 22.5% in 2022), whereas influenza A and adenovirus were found in lower frequency (12.5 and 5.5% in 2021; 13.4 and 4.9% in 2022, respectively). Because these different respiratory virus diseases produce similar symptoms, diagnosis based on clinical condition alone can be inaccurate, and more reliable testing is required to select the best therapeutic approach for each case. The loosening of restrictive measures to contain the COVID-19 pandemic led to higher numbers of other respiratory infections in pediatric patients. Ongoing surveillance and differential diagnosis of respiratory viruses are required to better understand their seasonal patterns after the COVID-19 pandemic to guide prevention and control strategies.

Respiratory virus infections after allogeneic stem cell transplantation: Current understanding, knowledge gaps, and recent advances.

Before the COVID-19 pandemic, common community-acquired seasonal respiratory viruses (CARVs) were a significant threat to the health and well-being of allogeneic hematopoietic cell transplant (allo-HCT) recipients, often resulting in severe illness and even death. The pandemic has further highlighted the significant risk that immunosuppressed patients, including allo-HCT recipients, face when infected with SARS-CoV-2. As preventive transmission measures are relaxed and CARVs circulate again among the community, including in allo-HSCT recipients, it is crucial to understand the current state of knowledge, gaps, and recent advances regarding CARV infection in allo-HCT recipients. Urgent research is needed to identify seasonal respiratory viruses as potential drivers for future pandemics.

Trend in respiratory viruses' activity in the COVID-19 area.

SARS-CoV-2 has impacted the detection of seasonal respiratory viruses. We retrospectively assessed the trend in the detection of 10 viruses in the COVID-19 area in 2 hospitals located in the Paris area. All patients positive for a respiratory virus in two hospitals from September 2016 to August 2021 were retrospectively included. The rate of RT-PCR positive for each virus was calculated for the 2020-2021 season and the 2019-2020 season in comparison to a baseline of 3 seasons, i.e. 2016-2017, 2017-2018, and 2018-2019. Overall, 7,835 patients were tested positive from September 2016 to August 2021. The detection of respiratory virus dramatically falls on week-11 of 2020, as the number of RT-PCR performed. Then, 3 trends were identified: a) almost a disappearance for influenza; b) a 10-weeks delay in the seasonal outbreak for RSV; c) a persistence of circulation with variable activity for other viruses. In comparison to a baseline of three seasons (2016-2019), the rate of positive patients was lower during the 2020-2021 season for coronavirus (4.51% vs. 1.26%, P <0.0001), adenovirus (1.93% vs. 1.34%, P =0.14), bocavirus (0.58% vs. 0.11%, P =0.08), and enterovirus (0.28% vs. 0.0%, P =0.12). In contrast, the rate of hMPV-positive (1.92% vs. 2.83%, P =0.03) and hPIV-positive (2.17% vs. 2.99%, P =0.06) patients increased. The fall in the number of respiratory viruses detected might be related to the lower number of tests performed and the implementation of non pharmaceutical intervention (NPI). Then, all viruses except influenza are detected, probably as a consequence of high adherence to influenza vaccines. Despite, a lower number of tests being performed, the rate of hMPV-positive and hPIV-positive patients increased suggesting an active circulation of these viruses. Altogether, these findings suggest a persistent circulation of common respiratory viruses all over the COVID-19 era.

Seasonal Respiratory Virus Circulation in a Tertiary Care Hospital in Greece

Background: The COVID-19 pandemic caused by the novel SARS-CoV-2 virus affected health care systems and public health worldwide dramatically. Several measures were applied in order to prevent or stop the rapid transmission of the virus and the subsequent disease, such as lockdowns, physical distancing, strictly hygiene, along with travel restrictions. Global population after vaccination programs against COVID-19 were carried out, is facing a “tripledemic” situation threat, with the co-existance of SARS-CoV-2, influenza and RSV. The aim of the present study was to evaluate the co-existence of SARS-CoV-2, influenza and RSV, as well as the correlation with gender, age, Cts and vaccination doses. Methods: A total of 302 patients were included in the study. All patients were admitted to the emergency department of General Hospital Nikea, Piraeus with common upper respiratory tract symptoms and were suspected for COVID-19 disease, between March to July 2022. Patients’ age, gender, vaccination doses, and results from RT-PCR detection for SARS-CoV-2, RSV and Influenza viruses were recorded. Results: 139 were male and 163 female, aged between 18-94 years. Out of the patients included in the study, 206 were vaccinated and 96 were not vaccinated. Among vaccinated patients 97 were male and 109 were female. A percentage of 3.3% had received one vaccination dose, 16.9% two and 47.7% three. Moreover, 88 patients presented infection symptoms; 81 patients had a positive rapid test result. We detected 15 cases of co-infection of SaRS-CoV-2 and RSV and only one case, of co-infection of SaRS-CoV-2 with influenza virus. Conclusions: The majority of patients admitted to the emergency department of GHNP with common upper respiratory tract clinical manifestations were female. A significantly lower rate of co-infection with SARS-CoV-2 and RSV was detected in patients having received 2 vaccination doses, compared to patients having received 3 out of 3 vaccination doses or up to 1 vaccination dose. Ct values for SARS-CoV-2 and RSV pathogens were between 10-17. Co-infection with SARS-CoV-2 and Influenza was detected in only 1 patient.

Severe acute respiratory syndrome in children treated at a pediatric referral hospital in Brazil during the COVID-19 pandemic

Background - Although we have accumulated knowledge along with the pandemic, there are still gaps, including the impact of seasonal conditions of SARS-CoV-2 and other respiratory viruses. Methods - A retrospective cohort study that aimed to describe the etiological diagnosis and compare the clinical presentation and outcomes of children with Severe Acute Respiratory Syndrome (SARS). Results – 1,027 children diagnosed with SARS were evaluated. In 926 (90.2%) children who collected RT-PCR Covid, 2.3% had a positive result. A total of 365 (35.4%) of the children underwent collection for Viral Panel exam, with identification of the etiology in 28%. There was a statistically significant difference in the age of patients infected with RSV and other viruses. The length of hospital stay was statistically different (p:0.006) when comparing groups of rhinovirus with COVID or RSV. Conclusion - This study is a pioneer in conducting large-scale testing for respiratory viruses in pediatric patients during the pandemic and contributes to the knowledge about the etiology of SARS in childhood, and this disease's relationship with the seasonality of respiratory viruses.

Preventing measles transmission in ambulatory pediatric settings during peak respiratory viral season

Background: Measles is a highly transmissible respiratory virus that presents with nonspecific prodromal symptoms followed by a characteristic cephalocaudal rash. In the prodromal phase, children with measles can be challenging to differentiate from children with other circulating respiratory viral infections. A measles outbreak in Central Ohio starting in October 2022 coincided with a national surge in children with viral respiratory infections which presented unique challenges in preventing healthcare transmission in the pediatric ambulatory setting. Methods: Following initial identification of presumed community transmission of measles in Central Ohio in November 2022, a multidisciplinary measles response team was convened at Nationwide Children’s Hospital (NCH) to prevent secondary healthcare transmission via rapid-cycle quality improvement. Prevention efforts were focused broadly across NCH ambulatory locations in Central Ohio, including the main campus and offsite emergency departments, regional urgent cares, and primary care network. Preliminary risk factors were identified via chart review of initial cases, which included vaccine status, ZIP code of residence, and known daycare or household exposure. These risk factors were used to guide an intervention bundle comprising enhanced screening at registration and triage, creation of electronic medical record alerts to identify at-risk patients, increased clinician education, and expanded community messaging. As the outbreak evolved, risk factors were updated, and interventions were adjusted to adapt response. Outcome metrics included total patient exposures as well as the relative exposure score. The exposure score was an internal metric derived using the vaccine status of exposed patients and ventilation at the site of exposure to assess likelihood of secondary cases occurring from an exposure. Results: In total, 65 patients with measles were seen at NCH facilities between October 29 and December 8, 2022. The outbreak response was divided into 4 periods: (1) cases identified retrospectively prior to first diagnosis (October 29–November 7, 2022), (2) initial case discovery (November 8–14, 2022), (3) implementation of prevention bundle (November 15–28, 2022), and (4) updates to the response (November 29–December 8, 2022). Ambulatory healthcare exposures and incidence of secondary cases decreased over the outbreak periods in response to implementation of the prevention bundle (Fig. and Table). Conclusions: An outbreak of measles occurring simultaneously with peak respiratory viral season presented challenges in early identification of suspected cases and mitigation of healthcare exposure. Transmission was effectively prevented following rapid deployment of a prevention bundle adjusted in real-time through rapid-cycle quality improvement. Ongoing longitudinal vaccination efforts are needed to sufficiently mitigate transmission risk in communities with under-vaccinated populations.Disclosures: None

Changing pattern of respiratory virus detections among school‐aged children in a small community – Dane County, Wisconsin, September to December 2022

AbstractWidespread school closures and other non‐pharmaceutical interventions (NPIs), used to limit the spread of SARS‐CoV‐2, significantly disrupted transmission patterns of seasonal respiratory viruses. As NPIs were relaxed, populations were vulnerable to resurgence. This study within a small community assessed acute respiratory illness among kindergarten through grade 12 students as they returned to public schools from September through December 2022 without masking and distancing requirements. The 277 specimens collected demonstrated a shift from rhinovirus to influenza. With continued circulation of SARS‐CoV‐2 and return of seasonal respiratory viruses, understanding evolving transmission patterns will play an important role in reducing disease burden.

Respiratory Syncytial Virus, Influenza, and Coronavirus Disease 2019 Hospitalizations in Children in Colorado During the 2021-2022 Respiratory Virus Season

To compare demographic characteristics, clinical features, and outcomes of children hospitalized with respiratory syncytial virus (RSV), influenza, or severe acute respiratory syndrome coronavirus 2 during their cocirculation 2021-2022 respiratory virus season. We conducted a retrospective cohort study using Colorado's hospital respiratory surveillance data comparing coronavirus disease 2019 (COVID-19)-, influenza-, and RSV-hospitalized cases < 18years of age admitted and undergoing standardized molecular testing between October 1, 2021, and April 30, 2022. Multivariable log-binomial regression modeling evaluated associations between pathogen type and diagnosis, intensive care unit admission, hospital length of stay, and highest level of respiratory support received. Among 847 hospitalized cases, 490 (57.9%) were RSV associated, 306 (36.1%) were COVID-19 associated, and 51 (6%) were influenza associated. Most RSV cases were <4years of age (92.9%), whereas influenza hospitalizations were observed in older children. RSV cases were more likely to require oxygen support higher than nasal cannula compared with COVID-19 and influenza cases (P<.0001), although COVID-19 cases were more likely to require invasive mechanical ventilation than influenza and RSV cases (P < .0001). Using multivariable log-binomial regression analyses, compared with children with COVID-19, the risk of intensive care unit admission was highest among children with influenza (relative risk, 1.97; 95% CI, 1.22-3.19), whereas the risk of pneumonia, bronchiolitis, longer hospital length of stay, and need for oxygen were more likely among children with RSV. In a season with respiratory pathogen cocirculation, children were hospitalized most commonly for RSV, were younger, and required higher oxygen support and non-invasive ventilation compared with children with influenza and COVID-19.

Healthcare-associated Respiratory Syncytial Virus in Children's Hospitals.

Outbreaks of healthcare-associated respiratory syncytial virus (HA-RSV) infections in children are well described, but less is known about sporadic HA-RSV infections. We assessed the epidemiology and clinical outcomes associated with sporadic HA-RSV infections. We retrospectively identified hospitalized children <18 years old with HA-RSV infections in six children's hospitals in the United States during the respiratory viral seasons October-April in 2016-2017, 2017-2018, and 2018-2019 and prospectively from October 2020 through November 2021. We evaluated outcomes temporally associated with HA-RSV infections including escalation of respiratory support, transfer to the pediatric intensive care unit (PICU), and in-hospital mortality. We assessed demographic characteristics and comorbid conditions associated with escalation of respiratory support. We identified 122 children (median age 16.0 months [IQR 6, 60 months]) with HA-RSV. The median onset of HA-RSV infections was hospital day 14 (IQR 7, 34 days). Overall, 78 (63.9%) children had two or more comorbid conditions; cardiovascular, gastrointestinal, neurologic/neuromuscular, respiratory, and premature/ neonatal comorbidities were most common. Fifty-five (45.1%) children required escalation of respiratory support and 18 (14.8%) were transferred to the PICU. Five (4.1%) died during hospitalization. In the multivariable analysis, respiratory comorbidities (aOR: 3.36 [CI95 1.41, 8.01]) were associated with increased odds of escalation of respiratory support. HA-RSV infections cause preventable morbidity and increase healthcare resource utilization. Further study of effective mitigation strategies for HA-respiratory viral infections should be prioritized; this priority is further supported by the impact of the COVID-19 pandemic on seasonal viral infections.