Infection rate and factors affecting close contacts of COVID-19 cases: A systematic review.

OBJECTIVE: Contact tracing plays an essential role in mitigating the impact of an epidemic. During the COVID-19 pandemic, studies of those who have been in close contact with confirmed cases offer critical insights to understand the epidemiological characteristics of SARS-CoV-2 better. This study conducts a meta-analysis of existing studies' infection rates and affecting factors. METHODS: We searched PubMed, Web of Science and CNKI from the inception to April 30 2022 to identify systematic reviews. Two reviewers independently extracted the data and assessed risk of bias. Meta-analyses were conducted to calculate pooled estimates by using Stata/SE 15.1 software. RESULTS: There were 47 studies in the meta-analysis. Among COVID-19 close contacts, older age (RR = 1.94, 95% CI: 1.70, 2.21), contacts in households (RR = 2.83, 95% CI: 2.20, 3.65), and people in close contact with symptomatic infections (RR = 3.62, 95% CI: 1.88, 6.96) were associated with higher infection rates. CONCLUSION: On average, each primary infection corresponded to 5.8 close contacts. Among COVID-19 close contacts, older age and contacts in households were associated with higher infection rates, and people in close contact with symptomatic infections had three times higher risk of infection compared to people in close contact with asymptomatic infections. In general, there are significantly more studies from China about close contacts, and the infection rate among close contacts was lower compared to other countries.

Mobility in China, 2020: a tale of four phases.

2020 was an unprecedented year, with rapid and drastic changes in human mobility due to the COVID-19 pandemic. To understand the variation in commuting patterns among the Chinese population across stable and unstable periods, we used nationwide mobility data from 318 million mobile phone users in China to examine the extreme fluctuations of population movements in 2020, ranging from the Lunar New Year travel season (chunyun), to the exceptional calm of COVID-19 lockdown, and then to the recovery period. We observed that cross-city movements, which increased substantially in chunyun and then dropped sharply during the lockdown, are primarily dependent on travel distance and the socio-economic development of cities. Following the Lunar New Year holiday, national mobility remained low until mid-February, and COVID-19 interventions delayed more than 72.89 million people returning to large cities. Mobility network analysis revealed clusters of highly connected cities, conforming to the social-economic division of urban agglomerations in China. While the mass migration back to large cities was delayed, smaller cities connected more densely to form new clusters. During the recovery period after travel restrictions were lifted, the netflows of over 55% city pairs reversed in direction compared to before the lockdown. These findings offer the most comprehensive picture of Chinese mobility at fine resolution across various scenarios in China and are of critical importance for decision making regarding future public-health-emergency response, transportation planning and regional economic development, among others.

[Risk factors for nutritional iron deficiency anemia in children].

OBJECTIVE: To investigate the clinical features of nutritional iron deficiency anemia (IDA) and analyze the risk factors for the severity of anemia, and to provide a basis for the prevention and clinical diagnosis and treatment of this disease. METHODS: A retrospective analysis was performed on the clinical data of 372 children with IDA to investigate the risk factors for the severity of IDA. RESULTS: Of 372 cases, the male-to-female ratio of these patients was 2.72 : 1. Of all cases, 79.9% were aged 6 months to 2 years, and 30.7% were premature infants; 22.9% had a birth weight of < 2.5 kg, and 77.1% had a birth weight of ≥2.5 kg; 36.0% were delivered by natural birth, and 64.0% were delivered by caesarean section; 79.3% were not given solid foods in time; 46.2% had a history of lower respiratory tract infection/recurrent upper respiratory tract infection, diarrhea, trauma, or surgery. The univariate analysis showed that age, birth weight, gestational age, timely introduction of solid foods, and a history of lower respiratory tract infection/recurrent upper respiratory tract infection, diarrhea, trauma, or surgery were associated with the severity of anemia. The multivariate analysis showed that birth weight and the mentioned medical history were associated with the severity of anemia. CONCLUSIONS: Nutritional IDA is common in children aged 6 months to 2 years. Nowadays, improper feeding pattern is still one of the main causes of IDA. Birth weight and a history of lower respiratory tract infection/recurrent upper respiratory tract infection, diarrhea, trauma, or surgery are closely associated with the severity of anemia.

[Clinical features and outcome analysis of 83 childhood Epstein-Barr virus-associated hemophagocytic lymphohistiocytosis with HLH-2004 protocol].

OBJECTIVE: To investigate the clinical features of Epstein-Barr virus-related hemophagocytic lymphohistiocytosis (EBV-HLH), to analysis the outcome of HLH-2004 protocol, and to explore the prognostic factors in EBV-HLH patients. METHODS: The clinical features at onset and outcome of HLH-2004 protocol from 83 pediatric patients with EBV-HLH enrolled from January 2006 to December 2009 in our hospital were analyzed retrospectively. Univariate and multivariate COX regression analysis were used to identify statistically significant prognostic factors. RESULTS: (1) Among the 83 patients, 45 were males and 38 were females. The age of onset ranged from 6 months to 14 years 4 months. 44 patients were treated with HLH-2004, and 3-year overall survival (OS) was (55.8 ± 7.9)%. (2) The most common clinical features of EBV-HLH included high fever, cytopenia, hepatosplenomegaly, and coagulopathy; The respiratory symptoms, angina phlogistic, skin rashes, neurologic abnormality were rare. 97.3% of patients showed an elevation of serum ferritin, liver dysfunction and lipid metabolism disorders was found in most of EBV-HLH patients. 89.0% of patient had hemophagocytosis in bone marrow at diagnosis of EBV-HLH. (3) COX regression analysis revealed that anemia degree, serum albumin < 30 g/L, CD4:CD8 abnormity, NK cell < 3%, treatment protocol were related with the prognosis significantly (P < 0.05). CONCLUSION: EBV-HLH in pediatric patients has severe clinical feature and poor prognosis. HLH-2004 protocol is an effective treatment for patients with EBV-HLH. Symptomatic treatment can't rescue the patients of EBV-HLH.

[Analysis of thirteen cases with secondary coagulation disorder caused by raticide exposure].

OBJECTIVE: To summarize the clinical characteristics of secondary coagulation disorders caused by exposure to poison (raticide) in children and to investigate the diagnosis and corresponding treatment. METHOD: The process of diagnosis, clinical characteristics, response to treatment and the prognosis were analyzed. RESULTS: The main clinical manifestation was mucosal bleeding (66.6%), including epistaxis, gingival bleeding, hematomas and so on. All these children were previously well and had no history of bleeding. Activated partial thromboplastin time (APTT) and prothrombin time (PT) were prolonged, factor II was undetectable and the levels of factors VII, IX, and X were lower. The fibrinogen was normal. A raticide was detected in blood and urine of 13 children although 12 of the patients had no definite history of raticide ingestion. Prothrombin complex, fresh frozen plasma and vitamin K(1) were effective in these cases. However, 2 - 3 weeks later, 6 patients presented with recurrent bleeding. CONCLUSION: For children with secondary coagulation disorders of unknown cause, intoxication of raticide should be considered. The administration of blood coagulation factors and vitamin K(1) are effective in early treatment, and the treatment period should be more than 2 months. The PT and APTT should be followed up. Vitamin K(1) should be stopped when PT and APTT are normal.

A retrospective analysis of therapeutic responses to two distinct corticosteroids in 259 children with acute primary idiopathic thrombocytopenic purpura.

OBJECTIVE: To analyze the responses of pediatric patients with newly-diagnosed acute primary idiopathic thrombocytopenic purpura (ITP) to two distinct corticosteroids. METHODS: We retrospectively reviewed a cohort of 259 patients with acute ITP diagnosed between 2004 and 2008. Specifically, we compared response rates and adverse effects in patients treated with methylprednisolone or dexamethasone. RESULTS: Corticosteroids were used as the first-line treatment in all patients with an initial response rate of 96.5%. Choice of the intravenous corticosteroid for treatment did not affect the outcome of patients. The time platelet count maintained at a normal level showed no statistical difference between patients administered with methylprednisolone or dexamethasone. Only minor adverse effects were observed in both groups of patients. CONCLUSIONS: Both corticosteroids yielded similarly high response rates and minor adverse effects in ITP patients. This should be taken into account when choosing the treatment regimen for children with acute ITP.

[Enhancement effects of hypoxia on invasion and metastasis of K562 cells].

OBJECTIVE: To study the potential effect of hypoxia on invasion and metastasis of leukemia cell line K562. METHODS: K562 cells were cultured with the conventional method in vitro and treated with 1%, 3% and 5% oxygen for 24 hrs. The normoxic cultured K562 cells were used as the control group. Cell adhesion assay, cell migration assay and cell invasion assay were used to detect the adhesion, migration and invasion abilities of K562 cells. RT-PCR was used to measure the mRNA expression of HIF-1alpha, VEGF, MMP-2 and MMP-9. The protein level of HIF-1alpha was measured by Western blot. RESULTS: Compared with the control group, the 3% and 5% oxygen treatment groups significantly increased the adhesion, migration and invasion abilities of K562 cells (p<0.05 or <0.01), and up-regulated the protein level of HIF-1alpha and the mRNA levels of HIF-1alpha,VEGF, MMP-9 and MMP-2 (p<0.05 or 0.01). However, there were no significant differences in the above indexes between the 1% oxygen treatment and the control groups. CONCLUSIONS: Moderate hypoxia can enhance the abilities of invasion and metastasis of K562 cells, probably by an up-regulation of HIF-1alpha level and VEGF, MMP-2 and MMP-9 mRNA expression.

[Successful treatment of a patient with Wiskott-Aldrich syndrome using hematopoietic stem cell transplantation--case report and literature review].

OBJECTIVE: Wiskott-Aldrich syndrome (WAS) is a primary immunodeficiency diseases. The patients with classical WAS have poor prognosis. The hematopoietic stem cell transplantation is the most effective method to cure WAS at present. In this report, a patient with WAS was cured with HLA identical sibling bone marrow transplantation (BMT). METHODS: Wiskott-Aldrich syndrome protein (WASP) was detected using flow cytometry and WASP were analyzed for the diagnosis. The bone marrow was collected from the elder sister who was the HLA identical sibling donor. A total of 4.38x10(8)/kg mononuclear cell (MNC) and 3.78x10(6)/kg CD34+ cells were collected and transfused into the patient after the conditioning regimen with busulfan/cyclophosphamide. Cyclosporine only was used for graft-versus-host disease prophylaxis. WASP and short tandem repeats (STR) were detected as the evidence of engraftment. RESULTS: The diagnosis was WAS: WASP (-IVS9+2T>C, WASP-negative). The patient received busulfan/cyclophosphamide 9 days before the transplantation. WBC decreased to 0.1x10(9)/L in d+4; The absolute number of neutrophils (ANC) was 0.8x10(9)/L in d+13, and exceeded 1.0x10(9)/L later on. From d(-9)-d+14 the patient was dependent on platelet transfusion. From d+15 the patient's PLT>50x10(9)/L and returned to normal after d+30. In d+9-d+10 mild GVHD (I degree) occurred but subsided after the steroid treatment. From d+50, WASP was detected positive and STR showed full donor DNA chimera. Follow-up for 510 d post-transplant, the patient suffered only from mild cold twice, no eczema, no bleeding occurred. The PLT is normal and no chronic GVHD occurred. The levels of IgG, IgM and IgA of the patient were approximately normal. CONCLUSION: The HLA-identical sibling's BMT seems to be the periorit treatment of choice for the WAS patient.

[Clinical study on childhood acute lymphoblastic leukemia diagnosed and treated with 04 Protocol in Chongqing, China].

OBJECTIVE: To analyze the clinical and laboratory data from acute lymphoblastic leukemia (ALL) patients and the results of treatment using 04 Protocol (suggested by the Pediatric Hematology Group of Chinese Medical Association in 2004). METHODS: This study included 88 children with ALL below the age of 18 years during the period from October 1, 2004 to June 30, 2007. Minimal inhibitory concentration (MIC) and clinical risk classification were done and the new chemotherapy regimen was used according to the protocol. Patients were stratified into low-risk (LR), medium-risk (MR), and high-risk (HR) groups. Life table method was used to estimate survival rate and statistical analysis was done by using software SPSS for Windows. RESULTS: From October 2004 to June 2007, 88 childhood ALL patients were treated with the 04 Protocol. Sixty-three (91.30%) patients attained complete remission (CR) and 17 patients lost to follow up. The overall 4-year-event-free survival (EFS) rate (+/- SE) was (59.73 +/- 7.22)%. EFS was (75.60 +/- 9.71)% in the LR (n = 30), (65.50 +/- 11.69)% in the MR (n = 20) and (44.03 +/- 12.36)% in the HR. Relapse occurred in 18.18% of patients. Seven (7.95%) of 88 patients with ALL died during he induction therapy. Infection was the most common cause of death. CONCLUSION: The outcome of patients treated with the 04 Protocol was favorable. Clinical risk classification and the leukemia cells of D19 are independent predictors of prognosis of ALL. High dose methotrexate played an important role in prevention and treatment of central nervous system leukemia. The mortality rate of this chemotherapeutic protocol during induction therapy was high.

[Hematopoiesis support of mesenchymal stem cells in children with aplastic anemia].

OBJECTIVE: The abnormality of hemopoietic inductive microenvironment (HIM) is involved in the pathophysiology of aplastic anemia (AA). Mesenchymal stem cells (MSC) are main source of bone marrow stromal cells which constitute the bone marrow HIM. Thus, the bone marrow failure in AA may be related to the function of MSC. The aim of the study was to investigate the hematopoiesis support function of MSC in children with AA in vitro. METHODS: Bone marrow samples were collected from 24 children with AA at diagnosis and 19 children with idiopathic thrombocytopenic purpura (ITP), infectious mononucleosis or lymphadenitis (controls). MSCs from bone marrow samples were isolated, cultured and expanded. Morphology, proliferation activity and colony forming unit-fibroblast (CFU-F) were measured. The ability of bone marrow MSC to adhere hemopoietic cells was assayed by MTT. The concentration of stem cell factor (SCF) released from MSC was tested using ELISA. Mononuclear cells (MNC) of bone marrow were plated onto a feeder layer formed by MSC. Cells count and BFU-E, CFU-GM, CFU-GMME productions were measured. RESULTS: The first and third passage time of MSC in children with AA was longer than that in the controls. The number of CFU-F in children with AA (15.70+/-5.78) was less than that in the controls (21.73+/-5.74) (P<0.05). The concentration of SCF in MSC supernatants in children with AA (30.69+/-16.82 pg/mL) was significantly lower than the controls (50.74+/-14.83 pg/mL) (P<0.01). The total MNC count and the number of BFU-E, CFU-GM and CFU-GMME colonies in the support of MSC in children with AA were significantly lower than those in the controls (P<0.01). CONCLUSIONS: The hematopoiesis support function of MSC was significantly reduced in children with AA in vitro. The decreased hematopoiesis support function of MSC may be related its decreased proliferation capacity and SCF release activity.

[Effects of matrine on invasion and metastasis of leukemia cell line Jurkat].

OBJECTIVE: To study the inhibitory effects of matrine, in different concentrations, on invasion and metastasis of human acute lymphocytic leukemia cell line Jurkat. METHODS: In vitro cultured Jurkat cells were treated by matrine in concentration of 0 g/L, 0.1 g/L, 0.15 g/L and 0.2 g/L, respectively. Then cell adhesion assay, cell migration assay and matrigel invasion assay were used respectively to observe the effects of matrine on adhesion, migration and invasive capacity of Jurkat cells. Meantime, RT-PCR was performed to detect the matrix metalloproteinase (MMP)-2 and MMP-9 mRNA expression levels. Comparison of measurement data among groups was analyzed by variance analysis. RESULTS: As compared with the control group, the adhesion of Jurkat to fibronectin (FN) was significantly inhibited by 0.15 g/L and 0.2 g/L of matrine (P < 0.05); the cell migration and invasive capacity were significantly lowered by 0.1 g/L, 0.15 g/L and 0.2 g/L matrine (P < 0.01). High mRNA expression of MMP-9 presented but that of MMP-2 was expressed insignificantly in Jurkat cells, matrine at 0.1 g/L, 0.15 g/L and 0.2 g/L showed obvious effect in down-regulating MMP-9 mRNA expression (P < 0.01). Besides, MMP-9 mRNA expression was found to be positively correlated with the invasive capacity of Jurkat cells (r = 0.940, P < 0.01). CONCLUSIONS: Matrine is a good drug for antagonizing the invasion and metastasis of leukemia cells, it may roundly inhibit the adhesion, migration and invasive capacity of Jurkat cells, the mechanism might be related with the down-regulation of MMP-9 mRNA expression.