The current Omicron wave that has a higher infection rate than all other Covid variants so far has not even spared kids, with many young children being hospitalised with severe croup problems.

This has been revealed in a new paper published by researchers at Boston Children’s Hospital, who found 75 new cases of croup in kids. This is a revelation as such cases are being reported for the first time in kids affected due to Covid-19.

“Between 3/1/2020-1/15/2022, a total of 75 children were diagnosed with COVID-19-associated croup, 81 per cent of whom presented during the Omicron period. There was a significant difference in median weekly cases between the pre-Omicron and Omicron periods. Most patients were male (72 per cent) and discharged from the emergency department,” the study revealed.

The study, conducted by Ryan CL Brewster and others, found that the “relatively smaller upper respiratory tract in children compared to adults has been thought to predispose them to more severe clinical presentations resembling laryngotracheobronchitis, or croup”.

The study said endemic coronaviruses have been linked to croup, however, only sparse case reports have described croup specifically associated with SARS-CoV-2 and it remains unclear if croup cases constitute a causative relationship or result of co-infection with another virus.

The retrospective analysis of a freestanding children’s hospital found the incidence of croup co-occurring with SARS-CoV-2 infection sharply increased in December 2021, strongly correlating with the emergence of the Omicron variant. Other spikes in COVID-19 were not associated with increased diagnoses of croup.

Researchers said their preliminary findings lend compelling evidence to the hypothesis that the Omicron variant causes laryngotracheobronchitis or croup.

The researchers, however, said two years into COVID-19, the pathogenicity, infectivity, and manifestations of new variants of SARS-CoV-2 have been dynamic and unique. Croup may represent yet another such novel presentation. It said more research is needed to characterise the underlying mechanisms of COVID-19-associated croup, differences in clinical features from other viral etiologies, and appropriate management strategies in the SARS-CoV-2 era.

Also read: Suffering from sore throat? Here’s how to find out whether it is COVID or cold

What is croup?

Caused by viral-induced subglottic airway inflammation, croup is classically characterised by sudden onset “barking cough”, inspiratory stridor, and respiratory distress. As SARS-CoV-2 has evolved, so has its effects on the pediatric population. “While early variants typically resulted in lower respiratory infections, the recently identified Omicron variant may exhibit a predilection for the upper airways,” the study revealed.

Study has potential limitations

The researchers conducted their analysis at a single centre, with small sample size, potentially restricting its generalisability. Nonetheless, it remains among the first and largest investigations of COVID-19-associated croup to date. An additional limitation is the absence of viral genotyping. 

The rapidity with which Omicron became the most dominant SARS-CoV-2 variant, however, lowers concern that there was a significant local circulation of other strains. Lastly, as comprehensive viral testing was not available, the study can’t entirely exclude the possibility of viral co-infection.