Croup, an inflammation of the mucosa of the subglottic upper airways, manifests as airflow obstruction in respiratory distress in children. In addition, it is associated with edema in the epithelium, and most emergency room visits are due to acute viral infection.
Study: Krupp Associated with SARS-CoV-2: Pediatric Laryngotracheitis During Omicron Rise. Credit: rumruay/Shutterstock
The frequency of presentations appears to be variable depending on local prevalence and specific viral pathogens. About 75% of cases are due to a specific parainfluenza virus (PIV) among its four subtypes, while the rest are due to common seasonal respiratory viruses. These cold viruses, as well as endemic coronaviruses, are included in the standard multiplex respiratory virus panel testing (RVP).
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From December 2021 to January 2022, Metro Atlanta experienced a sudden increase in the prevalence of cases of coronavirus disease 2019 (COVID-19), which was manifested by a sharp escalation of croup cases in the emergency room.
A new study published in the Journal of the Society for Pediatric Infectious Diseases aimed to characterize the clinical features of SARS-CoV-2-associated croup in children presenting to the emergency department during the phase when omicron variant transmission was high.
Emergency department visits related to acute SARS-CoV-2 infection were identified and the incidence of croup in these pediatric patients during the study period and during the previous Delta phase was compared.
Trends in emergency department visits were analyzed across both time periods to determine whether presentations could be attributed to SARS-CoV-2 strains. The cases were divided into two categories: period 1 – omicron-dominant (between December 2021 and January 2022) and period 2 – delta-dominant (between July 2021 and August 2022).
Subsequently, cases with a co-diagnosis of Krupp were identified and the frequency of this co-association between the two periods was compared. The impact on younger children during the two epidemics was characterized by comparing the significance of the proportional differences.
A total of 218,387 emergency room visits were recorded between 2021 and 2022; 15.9% of them resulted in hospital admissions. During the Omicron period, the number of emergency room visits for croup tripled, matching the increase in the prevalence of SARS-CoV-2. The admission rate in this phase increased from 12.1% to 15.6%. The overall admission rate for Krupp during this period was between 12.1% and 15.6%.
Interestingly, all other viral respiratory infections occurred less frequently during the Omicron period. However, during the delta period, respiratory syncytial virus (RSV) and rhinovirus/enterovirus (RV/EV) caused an unexpected number of hospitalizations.
During the delta period, 44,940 emergency department visits were recorded; 4.7% of these could be traced back to COVID-19. Of the COVID-19 cases, 28.8% were pediatric patients (0-4 years); 17.6% of them were hospitalized. Of all COVID-19 cases recorded during the Delta reporting period, 0.9% were diagnosed as croup.
A total of 15,423 emergency department visits occurred during the Omicron period, 12% of which were related to COVID-19. Of the patients with COVID-19, 51.2% were children (0-4 years old) – representing a 77.8% increase in the proportion (of COVID-19 cases in this age group) compared to the Delta period. Of these children with COVID-19, 16.1% were hospitalized; 10.8% were diagnosed with croup – a 12-fold increase in croup associated with COVID-19.
A total of 36 patients with croup underwent a multiplex PVR test; 66.7% were positive for SARS-CoV-2. Of the SARS-CoV-2 seropositive patients, 24 had an average age of 12 months, 18 were male and six were female. Ten were Caucasian, seven African American, five Hispanic, and two Asian.
Of those 24 pediatric patients, 11 were hospitalized – two in the intensive care unit (ICU) and one requiring supplemental oxygen with Heliox. The median length of hospital stay was 24 hours and patients were treated according to the standard protocol for treating croup.
Compared to the delta variant of SARS-CoV-2, the omicron variant shows higher transmissibility. The incidence of croup associated with a SARS-CoV-2 presentation has been observed to increase dramatically during the omicron phase of the COVID-19 pandemic. In addition, the diagnosis of COVID-19 in children aged 0 to 4 years almost doubled during the Omicron period compared to the Delta period.
Therefore, the importance of vaccination efforts cannot be overlooked, especially in this vulnerable population. In addition, tissue tropism of the upper airways was demonstrated by the Omicron variant. This helps the virus adapt to new tissues to improve its survivability and transmissibility. Sweden has recently reported numerous cases of odynophagia and laryngitis in young adults during a period of omicron dominance, suggesting the development of tissue tropism of the pathogen.
The results confirmed the existence of an infectious croup syndrome associated with SARS-CoV-2, which mimics croup due to other respiratory viruses that increased in frequency during omicron dominance. In addition, infants with COVID-19 had a significantly higher incidence of croup during the Omicron period than during the earlier Delta period.
Therefore, continued efforts to prevent the spread of COVID-19 to younger children due to the adverse effects of COVID-19 in this population have been confirmed.