2.1 Patients’ enrollment and data collection
This retrospective study involved hospitalized children with SARS-CoV-2 infection, and they were admitted to the Wuhan Children’s Hospital from January 28 to February 28, 2020, which was the only designated hospital for treating COVID-19 patients under 16 years in Wuhan. Children who contacted with confirmed or suspected COVID-19 cases have undergone confirmatory SARS-CoV-2 nucleic acid real-time reverse transcription polymerase chain reaction (RT-PCR) testing. All of the individuals enrolled in this study were tested positive. The clinical courses and outcomes were followed up until April 30. In consideration of the possible secondary literature and statistical studies that can be performed in the future,23 it should be noted that part of our cases had been reported concisely in a previous correspondence paper about the main clinical, laboratory and radiological findings.8 This study was approved by the institutional ethics board of the Wuhan Children’s Hospital (Approval No. WHCH 2020003).
Data comprised of demographic information, clinical presentation, medical history and comorbidities, chest computed tomography (CT) images, laboratory results, treatments (medications and oxygen therapy) and outcomes were obtained from the medical records system and checked by two independent researchers. The duration of hospitalization, and the time of RT-PCR conversion (days from the first positive result to the first negative result of RT-PCR assays for SARS-CoV-2 nucleic acid), were also calculated. In particular, the information of previously diagnosed allergic diseases or related, including allergic rhinitis (AR), asthma, atopic dermatitis (AD), urticaria, and food/drug allergy, and known allergens were collected, and reconfirmed by telephone enquiries.
The severity of COVID-19 was also recorded according to the Chinese expert consensus on the diagnosis, treatment and prevention of SARS-CoV-2 infection in children (2nd Version).13Severe cases were identified when meeting one of the following criteria: (a) shortness of breath with increased respiratory rate (RR) except for the influence of fever and crying (RR ≥ 60 breaths per minute for those younger than 2 months, RR ≥ 50 breaths per minute for those aged between 2 and 12 months, RR ≥ 40 breaths per minute for those aged between 1 and 5 years, and RR ≥ 30 breaths per minute for those older than 5 years); (b) oxygen saturation ≤ 92% at rest; (c) hypoxia with accessory respiration (groaning, flaring of nares, three concave sign), cyanosis, and intermittent apnea; (d) disturbance of consciousness with somnolence and convulsions; (e) food refusal or feeding difficulty, with signs of dehydration; (f) high-resolution CT showing bilateral or multi-lobe involvement, with rapid aggressiveness or pleural effusion. Critical type patients should meet one of the following conditions and admit to intensive care unit (ICU): (a) respiratory failure with mechanical ventilation required; (b) shock; (c) complications with other organ failures. Patients who only had mild symptoms without pneumonia changes in chest CT images were referred to as the acute upper respiratory infection (AURI) type, and those who had COVID-19 pneumonia not meeting the above criteria of severe cases as the mild type. Individuals only positive for SARS-CoV-2, without any symptoms or changes in chest CT images were defined as asymptomatic (inapparent) infection.