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SARS-CoV-2 and croup, a rare relationship or coincidence?

Published:February 17, 2021DOI:https://doi.org/10.1016/j.ajem.2021.02.022
      Dear Editor,
      With interest we have read the series of 3 children with croup ascribed to COVID-19, written by Venn and colleagues [
      • Venn A.M.R.
      • Schimdt J.M.
      • Mullan P.C.
      A case series of pediatric croup with COVID-19.
      ]. In April 2020 an anxious 18-month-old boy was admitted at our hospital with respiratory distress, inspiratory stridor, barking cough, fever and oxygen saturation of 89%. Diagnosed with severe croup, he was treated with oxygen supplementation and dexamethasone. As part of our policy during COVID-19 pandemic, we performed RT-PCR for SARS-CoV-2 in all children admitted with respiratory complaints. This boy was found PCR positive. Unlike the described patients by Venn et al, our patient rapidly improved: after a few hours oxygen supplementation could already be stopped and the boy was discharged after 12 h. Since SARS-CoV-2 had not yet been described as a cause of croup in children, we performed multiplex RT PCR testing for all common respiratory viruses, which was not only positive for SARS-CoV-2 but also for enterovirus. We performed analysis of the electronic health records of all children presented to our emergency department in 2020. From the 16 patients presented with croup, only the above mentioned patient had a positive PCR for SARS-CoV-2 (and for enterovirus).
      Croup has been described in a minority of cases in relation to other coronaviruses (NL63, OC43, 229V). In those cases with croup, most often co-infections were found, just as in our patient, and single infections are rare [
      • Miller E.K.
      • Gebretsadik T.
      • Carroll K.N.
      • Adler B.
      • Shell R.
      Viral etiologies of infant bronchiolitis, croup and upper respiratory illness during 4 consecutive years.
      ,
      • Sung J.Y.
      • Lee H.J.
      • Eun B.W.
      • Kim S.H.
      • Lee S.Y.
      • Lee J.Y.
      • et al.
      Role of human coronavirus NL63 in hospitalized children with croup.
      ,
      • Rihkanen H.
      • Rönkkö E.
      • Nieminen T.
      • et al.
      Respiratory viruses in laryngeal croup of young children.
      ]. In multiple large retrospective reviews and prospective studies of COVID-19 in children croup is not reported as presenting symptom of SARS-CoV-2 infection in children [
      • Liguoro I.
      • Pilotto C.
      • Bonanni M.
      • et al.
      SARS-COV-2 infection in children and newborns: a systematic review.
      ,
      • Ludvigsson J.F.
      Systematic review of COVID-19 in children shows milder cases and a better prognosis than adults.
      ,
      • Swann O.V.
      • Holden K.A.
      • Turtle
      • et al.
      Clinical characteristics of children and young people admitted to hospital with COVID-19 in United Kingdom: prospective multicentre observational cohort study.
      ]. In our case SARS-CoV-2 was believed to be an “innocent co-infection” and not the causative viral pathogen. We agree with the authors that SARS-CoV-2 testing is indicated in children presenting with croup for isolation measures and – if positive – to check for co-infections to establish the relationship between SARS-CoV-2 and croup. However, we do not believe that SARS-CoV-2 is a frequent causative agent of (more) severe croup in children, and advise to review the patient for other causes of barking cough or atypical croup after stabilization, including considering repeat PCR testing.

      Author contributions

      Drs CLHB, NWR, TWK and SWJTL have written and critically reviewed the manuscript for important intellectual content. All authors approved the final manuscript as submitted and agree to be accountable for all aspects of the work.

      Declaration of Competing interest

      All authors report no potential conflicts of interest.

      Acknowledgements

      The authors are grateful to the parents of our patient who consented to participate in this study.

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