Results

General information
There were three boys, six girls and their 14 families admitted to Jinan Infectious Disease Hospital of Shandong University were investigated in this study. The youngest of the nine children was a pair of eleven-month-old twins and the oldest is nine years and 9 months old (mean age was 4.5 years, median age 3.5 years, Table 1). There were 16 families were infected by SARS-CoV-2, and 14 adults were enrolled in this study (two patients hospitalized in another hospital). The 14 patients consisted of 8 males and 6 females with a mean age of 42.9 years (median age, 37 years [range, 30–72 years]).

Clinical manifestations
All nine pediatric patients came from eight families. As shown in Table 1, six children had no information on symptoms available, but have positive results in nucleic acid detection after the positive diagnosis of their families. By contrast, only one child has wild cough and two children have a mild fever (37.4–38.5°C). None of the nine children required intensive care or mechanical ventilation or had any severe complications.
For the 14 adult patients, the main clinical symptoms were fever (8/14, 57.1%), cough (5/14, 35.7%), chest tightness/pain (3/14, 21.4%), fatigue (3/14, 21.4%) and sore throat (1/14, 7.1%). Meanwhile, there were four patients had no clinical symptoms. From the epidemiological data, 7/14(50%) of the adults were infected through household contact, 5 (35.8%) was found to be infected after returning from Wuhan or Hubei in late January 2019 and 2 (14.2%) patients couldn’t find the exact source of infection.

Laboratory tests and imaging examinations
As shown in Table 2, 8/9 (88.9%) children had normal or decreased white blood cell counts, consistent with the main characteristic of viral infection. Six children (66.7%) showed increased CK-MB. ALT, AST and the other index of liver and kidney were all normal. All inflammation indicators, including CRP, PCT, ESR and IL-6 were all within the normal range. Two children (22.2%) showed bronchitis and one (11.1%) showed bronchial pneumonia. One (11.1%) boy (the older of the twins) showed pulmonary consolidation and ground glass opacity on the first day (Figure 1(A)) admitted in the hospital, and disappeared after five days (Figure 1(B)). Five other (55.6%) children showed no abnormal chest radiograph.
Figure 1: Chest CT images of a case 7 and case 8 (one pair of 11 month old twins) patient upon admission, who had no symptom. (A) Transverse chest CT images showed pulmonary consolidation and ground glass opacity (case 7 on 7 February). (B) Showed marked improvement after 5 days (case 7 on 13 February). (C) Lung CT of case 8 – the case 7’s younger brother on admission day (case 8 on 7 February).
Table 2. The laboratory results of nine children patients.
Case no. WBC (109/L) N (%) L (%) PLT (109/L) Hb (g/L) CRP (mg/L) ESR (mm/h) PCT (ug/L) IL-6 (pg/ml) ALT (U/L) AST (U/L) CK-MB (U/L) CD4 (%) CD8 (%) NK (%) IgM (g/L) IgA (g/L) IgG (g/L) C3 (g/L) C4 (g/L) Ferritin D-dimer Myoglobin (ug/l) BNP (pg/ml) SAA
1 8.48 32.1 59.9 361 128 0.12 5 0.04 1.5 13 35 34 31.9 34.6 16.5 1.0 0.6 7 0.8 0.2 45.5 0.3 9 133 3
2 7.55 20.4 73.6 193 120 0.35 2 0.08 1.5 14 33 28 28.3 27.1 27.3 1.2 0.8 7.3 0.8 0.3 33.6 0.3 11 24 4
3 3.78 38.7 43.9 293 119 0.19 7 0.05 1.5 15 28 23 33.2 35.6 – 1.1 1.6 12.9 1.0 0.2 85.6 0.4 9 29 3
4 4.14 23.6 69.3 65 129 0.18 6 0.04 1.5 14 28 30 46.6 20.2 8.5 1.1 0.8 6. 9 1.0 0.2 – 0.2 9 116 5
5 3.69 33.8 53.3 169 106 0.12 5 0.03 1.5 15 23 22 45.7 33.4 14,8 0.9 0.6 8.1 0.1 1.0 48.1 0.1 9 87 3
6 9.33 27.8 66.7 278 133 0.24 2 0.08 1.5 13 36 76 36.9 22.6 16.7 1.6 1.7 16.3 1.0 0.2 50.7 0.2 9 39 6
7 11.17 17.2 77.4 305 117 0.19 2 0.04 1.5 22 39 43 – – – 1.3 0.3 7.1 0.7 0.1 62.6 0.3 9 31 3
8 9.42 24.5 68.6 358 116 0.19 2 0.04 1.5 22 42 52 – – – 0.6 0.2 7.0 0.7 0.1 59.7 0.3 9 2 3
9 5.45 41.2 53.0 235 140 0.26 3 0.02 1.5 9 24 27 33.1 29.3 16.5 1.3 1. 6 8.9 1.0 0.2 45.6 0.3 18 23 5
Note: WBC, white blood cell; N, Neutrophil; L, Lymphocyte; PLT, plate; Hb, Hemoglobin; ESR, erythrocyte sedimentation; PCT, Procalcitonin; ALT, alanine aminotransferase; AST, aspartate aminotransferase; CK-MB, creatine kinase MB; IgM, Immunoglobulin M; IgG, Immunoglobulin G; Ig, Immunoglobulin A; C3, complement3; C4, complement4; BNP, N-terminal brain natriuretic peptide precursor; SAA, Serum amyloid A.
All the adult patients had normal (10/14, 71.4%) or decreased (4/14, 28.6%) white blood cell counts and 10 (71.4%) have lymphopenia. There were 4 (28.6%) patients had increased CRP, PCT, Serum amyloid A (SAA), D-dimer and IL-6, meanwhile, their CT-scan showed larger lung consolidation. Compared to children, there were only two (14.3%) patients showed increased CK-MB. Ferritin in the adult patients were higher than the children but most of them were normal (11/14, 78.6%). The imaging of adult chest was mix and the most common characters of imaging were pulmonary consolidation (50%), nodular shadow (42.9%), and ground glass opacity (GGO, 35.7%) (Figure 2). Four (28.6%) adults showed normal chest imaging.
Figure 2. Lung computed tomography (CT) images of case 7 and case 8’s families. (A) The CT of their grandpa, who was 72-year-old and admitted for symptoms of high fever for 3 days. (B) CT scan of case their father, a 38-year-old patient admitted for symptoms of high fever, shortness of breath and fatigue for 10 days on his admission day. (C) Lung CT image of their mother, a 32-year-old female patient admitted for positive result of PCR (C). (D) Chest CT of the twins’ grandma, 65 years old and had fever, dry cough and chest pain for 6 days before admission.

Treatment regimen and prognosis
At present, there are no drugs available that can target SARS-CoV-2. Therefore, treatment was focused on symptomatic and respiratory support. All the children inhaled interferon and one of the twins was prescribed ribavirin (10–15 mg/kg.d) in addition. Ten (71.4%) adults with pneumonia were treated Lopinaviritonavir (200/50 mg, 2 tablets, bid), interferon and Chinese medicine. The patients with higher infection index (such as CRP, PCT, ESR, SAA, IL-6) were prescript antibiotics for 5–7 days in addition. All the nine children and 14 adult patients recovered in 2–3 weeks and were discharged after two negative nucleic acid tests. Unfortunately, our follow up found that there were five discharged children were admitted again before we submit this article because their stool showed positive result in SARS-CoV-2 PCR. Meanwhile, all their families were negative in all the specimen.