Materials and Methods
Clinical definition and classification
Children are defined as being less than 18 years old. Referring to the guidelines on the diagnosis and treatment of SARS-CoV-2 infected pneumonia (the sixth edition draft) issued by the National Health Commission of China.6 Fever is recognized when body temperature is higher than or equal to 37.3℃.Respiratory symptoms include nasal congestion, runny nose, sneezing,sore throat, cough, expectoration, chest pain, dyspnea,etc.Digestive symptoms include nausea, vomiting, abdominal pain, diarrhea, etc.A real-time reverse transcriptase polymerase chain reaction (RT-PCR) was used to detect SARS-CoV-2 RNA positive in nasopharyngeal swab or anal swab samples to confirm diagnosis.All chest CT images were reviewed by two experienced pediatric radiologists. If unilateral or bilateral lung fields have any of the features as follows:(a) ground glass opacities;(b) consolidations with surrounding halo sign;(c) nodules;(d) residual fiber strips;(e) lymphadenopathy.The result is defined as positive CT findings of viral pneumonia.7-8 Family cluster infection is defined as the occurrence of any of the following criteria in 2 or more family members within a period of less than 1 week: (a) fever;(b) respiratory and or digestive symptoms;(c) positive CT findings of viral pneumonia.
Discharge criteria: All clinical symptoms of the COVID-19 children disappeared, absorption of lung lesions improved, and two consecutive nucleic acid tests of both nasopharyngeal swab and anal swab were negative at least 24 hours apart.
Follow-up procedure after discharge: All discharged COVID-19 children were isolated and observed at home for 2 weeks, and community health workers visited house twice a week to collect nasopharyngeal swabs for SARS-CoV-2 RNA detection.They were also followed-up once every two weeks for at least two additional weeks after isolation. Among them, the RP pediatric patients were re-admitted to hospital for further medical observation and close contacts were also followed-up.The rest of the recovered non-RP pediatric patients were closely followed-up outside the hospital.
Data collection
We conducted a retrospective study.The medical records of all COVID-19 children were reviewed.Clinical and laboratory data of the first two days after admission were collected.Based on the SARS-CoV-2 RNA test results during follow-up, the RP group was defined as at least one positive test result. The control group was defined as all tests were negative and no suspicious clinical symptoms appeared, and the differences between the two groups were compared.
Inclusion criteria: all confirmed pediatric cases.
Exclusion criteria: lost follow-up cases.
Statistical Analysis
All analyses were conducted by using of IBM Statistical Product and Service Solutions software Version 24 (SPSS Inc,Chicago,IL).Continuous variables were summarized as the median with interquartile ranges (IQRs) or mean with standard deviations (SDs), median [IQR] or [mean±SD], depending on whether their distributions were normal or not.Comparisons of categorical variables were performed using the Pearson Chi‑square test. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated for statistically significant variables.The parametric tests (independent sample Student t-test) or non-parametric tests (Mann-Whitney U test) were used to analyse variables.P <.05 was considered as statistically significant in all tests if applied.