Fig. 1. Croup due to SARS-CoV-2 infection in children < 5 years. (A) Monthly cases of COVID-19 in children < 5 years and monthly detection rate of respiratory viruses. With the sharp rise in the number of COVID-19 cases in Seoul, South Korea during the omicron wave, the proportion of croup cases admitted to two hospitals in Seoul significantly increased. The parainfluenza virus did not circulate in South Korea between January and February 2022. (B) Neck radiography of a 28-month-old child with COVID-19 presenting with severe croup. Subglottic narrowing is noted (arrow, left) and with medical treatment the airway became patent after 18 hours (arrowhead, right).

COVID-19 = coronavirus disease 2019.