Epidemiological and clinical features of pediatric COVID-19

This retrospective review was conducted in children aged 0–14 years with a definite diagnosis of COVID-19 from local health authorities between January 15, 2020, and March 15, 2020, in mainland China. Based upon the method previously described by Wei et al. and Xu et al. with slight modifications, we collected anonymous data on COVID-19 as epidemic updates were publicized by local health authorities using the web crawler technique [8, 11]. Web crawler is a program or script that automatically crawls web information according to certain rules [11]. In this study, we used the web crawler technology implemented by combining the Python language with Mysql database to collect COVID-19 data via the following procedures: (1) determination of the source of data collection through the website and portal of each local health administration department in China; (2) data interface analysis and data capture on information acquired from the website of each case release by imitating the hypertext transfer protocol_GET requests (HTTP_GET); (3) data cleaning by removing noise and irrelevant data, merging the data from multiple data sources into a data store, and then converting the original data into a form suitable for data mining; and (4) data warehousing by storing the cleaned data in the Mysql database. The diagnostic criteria of COVID-19 were based on “Diagnosis and Treatment Protocol for 2019-nCoV” [9, 12]. The patients were eligible for inclusion if they met the following criteria: (1) younger than 14 years old and (2) at least two consecutive positivity of SARS-CoV-2 by the nucleic acid test. Those patients older than 14 years old and whose information on age and gender were not available were excluded from the study. Two independent reviewers screened the subjects for eligibility. The data on gender, age, geographic location, and epidemiological history was collected together with clinical features on presenting symptoms, diagnosis, and therapeutic outcome. The study protocol was approved by the Institutional Review Board (AAHRPP-accredited) of the Third Xiangya Hospital of Central South University and registered with the Chinese Clinical Trial Registry (www.​chictr.​org, registration number: ChiCTR2000030464).

SPSS19 and R 3.6.1 were used for data analysis. The incubation period was defined as the time from exposure to the onset of symptoms and expressed as a median and inter-quartile range. A descriptive statistical analysis was performed, and ratios or percentages were compared.

Clinical profiles collected from a total of 7097 patients with a definite diagnosis of COVID-19 from local health authorities were used. Patients older than 14 years of age or with an undefined age and gender were excluded. Three hundred forty-one children aged from 4 days to 14 years with a median age of 7 years were included in the study (Table 1 and Additional file 1: Table S1). A female-to-male gender ratio of 1.2:1 (183 boys and 158 girls) was found (Table 1).

As shown in Table 1, family clustering was a major transmission route for pediatric COVID-19. There were 210 patients (66%) who were infected by close contact with family members with COVID-19. Among the 210 pediatric patients, two neonates born to mothers with COVID-19 were tested positive for SARS-CoV-2 on day 4 and day 5 after birth, respectively. Ten cases (3.1%) were infected via close contact with non-family members diagnosed with COVID-19. Ninety-two patients (28.9%) had a history of exposure in an epidemic area, including residence in and around Wuhan or a recent trip to Wuhan or its vicinity. Six (1.9%) children had an undefined history of exposure since they had not taken any trips to epidemic zones or had no contact with definitely diagnosed cases or with individuals having a recent history of visiting Wuhan or adjoining areas. Data were invalid for 23 (6.7%) children.

Eighty-five (25.2%) children had a defined incubation time, which is the time frame from exposure to an infectious source to the onset of symptoms (Table 1). The median incubation period was 9 days (ranging 0 to 20 days), and the interquartile range was 6 to 13 days.

Twenty of 341 (5.9%) children were asymptomatic (with no overt clinical symptoms and negativity of SARS-CoV-2 virus infection by the nucleic acid test). Computed tomography (CT) indicated that 6 (30%) patients among 20 asymptomatic children had abnormal chest radiograph (Table 2). The disease severity was categorized according to “Diagnosis and Treatment Protocol for 2019-nCoV” [9, 12]. Three hundred and eighteen patients were diagnosed as mild (clinical symptoms without any imaging evidence of pneumonia) or moderate (fever and respiratory tract symptoms with imaging evidence of pneumonia) severity accounting for 93.3% of all cases, 2 (0.6%) had severe (an onset of respiratory distress with acute hypoxia) symptoms, and 1 (0.3%) was classified as critical case (an onset of respiratory failure and shock) (Table 2).

One hundred and thirty-six had a detailed description of clinical symptoms (Table 2). The symptoms that the pediatric COVID-19 patients presented included fever (77.9%) with body temperature ranging from 37.3 to 40 °C, cough (32.4%), lacrimation (4.4%), stuffy nose (2.2%), sneezing (0.7%), sore throat (2.2%), dyspnea (2.2%), nausea and vomiting (2.9%), diarrhea (4.4%), conjunctivitis (0.7%), dizziness/headache/myalgia (2.2%), fatigue (2.2%), and physical discomfort (2.2%) (Table 2).

Children with COVID-19 had fewer underlying diseases (Table 2). Among the pediatric patients in our study, two (1.5%) had concomitant congenital heart disease. Severe complications were also rare in the pediatric patients recruited in our study, of whom 1 (0.7%) developed heart failure and 6 (4.4%) and 3 (2.2%) had the signs of myocardial injury and liver injury, respectively (Table 2). In the critical case that has been reported as a case study, the complications included shock, acute kidney injury, and acute respiratory distress syndrome [13].

Both symptomatic and asymptomatic children with SARS-CoV-2 infection were hospitalized while asymptomatic patients may not require any therapy. For symptomatic patients with abnormal chest radiograph, therapeutic management generally included supportive therapy and antiviral treatment. As shown in Table 2, the study retrieved treatment information from 62 patients, in which 33 (53.2%) patients received antiviral therapy (lopinavir and ritonavir tablets), 27 (43.5%) received traditional Chinese medicine (Lianhua Qingwen capsules), 17 (27.4%) received antibacterial therapy (azithromycin), 17 (27.4%) received nutritional support therapy, 17 (27.4%) received symptomatic treatment (e.g., fever reduction, cough relief, myocardial nutrition, liver protection, diarrhea relief), 7 (11.3%) received interferon-α therapy, 4 (6.5%) received oxygen therapy, 4 (6.5%) received immunoglobulin therapy, and 2 (3.2%) received a psychological intervention. The critically ill patient in this study received comprehensive treatment including glucocorticoids and mechanical ventilation [13].

The overall prognosis of children with COVID-19 was benign with a decent recovery. There was no mortality in this pool of pediatric COVID-19 (Table 2). In 218 cases including three children with severe or critical clinical type, the median time from onset to cure was 16 days (ranging from 6 to 39), and the interquartile range was 13 to 21 days.

As shown in Table 3, we compared the differences between pediatric COVID-19 and adult COVID-19. Pediatric COVID-19 cases were mostly transmitted in family clustering while adults can be infected in multiple routes. It is worth noting that there may have been maternal-fetal vertical transmission of SARS-CoV-2 in newborns. The median and interquartile range of the incubation period in pediatric COVID-19 were 9 days and 6–13 days, respectively; the median and interquartile range in adult COVID-19 were 4 days and 2–7 days, respectively. 5.9% of the pediatric patients were asymptomatic whereas approximately 1% of the adult COVID-19 patients were asymptomatic. Pediatric patients with COVID-19 were mainly mild/moderate, while adults, especially the elderly, tended to be more severe/critical. The clinical symptoms of COVID-19 in adults were more complicated than those in children although fever and cough were the main clinical manifestations for both adults and children. Compared with adults, children with COVID-19 had fewer comorbid conditions and complications. The treatment modalities for adult COVID-19 patients were more complicated than those for children with COVID-19. Children with COVID-19 recovered well whereas COVID-19 prognosis in adults was relatively worse with respect to the clinical outcome.