Background With the increased number of patients discharged after having COVID-19, more and more studies have reported cases whose retesting was positive (RP) during the convalescent period, which brings a new public health challenge to the world. Methods We searched PubMed, Web of Science, The Cochrane Library, CNKI, WanFang and VIP from December 1, 2019 to December 31, 2020. The included studies were assessed using JBI critical appraisal tools and Newcastle-Ottawa Scale. The RP rate of discharge patients was analyzed by a meta-analysis. We adhered to PRISMA reporting guideline. Findings We have included 117 studies with 2669 RP participants after discharge. The methodological quality of 66 case reports were low to high, 42 case series and 3 cohort study were moderate to high, 3 case-control studies were moderate and 3 cross-sectional studies were low to moderate. The clinical manifestations of most RP patients were mild or asymptomatic, and CT imaging and laboratory examinations were usually normal. The existing risk factors suggest that more attention should be paid to sever patients, elderly patients, and patients with co-morbidities. The summary RP rate was 12·2% (95% CI 10·6–13·7) with high heterogeneity ( I 2 = 85%). Interpretation To date, the causes and risk factors of RP result in discharged patients are not fully understood. High-quality etiological and clinical studies are needed to investigate these issues to further help us to make strategies to control and prevent its occurrence.

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Review question / Objective: P: Patients d i a g n o s e d w i t h I d i o p a t h i c thrombocytopenic purpura (ITP), and under 18 years old. I: High dose regimen-standard dose of intravenous immunoglobulin (IVIG). C: Low dose regimen-lower dose than the standard dose of IVIG. O:Is there any difference between high dose and low dose regimen of IVIG in treatment for ITP children? Can low-dose regimen replace high-dose regimen ? S: Randomized Controlled Trial. Rationale: In 1981, Paul Imbach et al. applied IVIG to 7 children with chronic ITP INPLASY 1 International Platform of Registered Systematic Review and Meta-analysis Protocols INPLASY PROTOCOL Efficacy, safety and economy of different doses of intravenous immunoglobulin in the treatment of idiopathic thrombocytopenic purpura in children: A systematic review and meta-analysis Ren, XG 1 ; Zhang, MM 2 ; Ni, JY 3 ; Zhai, WS 4 . To cite: Ren et al. Efficacy, safety and economy of different doses of intravenous immunoglobulin in the treatment of idiopathic thrombocytopenic purpura in children: A systematic review and meta-analysis. Inplasy protocol 202270126.

IntroductionIntravenous immunoglobulin (IVIg) is a first-line treatment for children with newly diagnosed immune thrombocytopenia (ITP). However, the cost of IVIg is high. Higher doses of IVIg are associated with a more insupportable financial burden to paediatric patients’ families and may produce more adverse reactions. Whether low-dose IVIg can quickly stop bleeding and induce a durable response in treating children with newly diagnosed ITP is not yet established.Methods and analysisWe will extensively search five English databases (PubMed, Embase, Web of Science, Cochrane Central Register of Controlled Trials, Cumulative Index of Nursing and Allied Health Literature) and three Chinese databases (CNKI, Wanfang and VIP). International Clinical Trials Registry Platform and ClinicalTrials.gov will also be searched as supplementary. Randomised controlled trials and prospective observational studies compared the efficacy of low-dose IVIg and high-dose or moderate-dose IVIg will be included. The primary outcome is the proportion of patients achieving durable response. Estimates of effect will be pooled with either a random-effect model or a fixed-effect model according to the heterogeneity of studies. If significant heterogeneity exists, we will conduct subgroup analysis and sensitivity analysis to explore the source of heterogeneity and evaluate the robustness of the results. Publication bias will also be assessed, if possible. The risk of bias will be assessed using the Risk of Bias 2 and Risk Of Bias In Non-randomised Studies of Interventions tools. The certainty of evidence will be evaluated using the GRADE (Grading of Recommendations, Assessment, Development and Evaluation) system.Ethics and disseminationNo ethical approval is required since this systematic review is based on previously published studies. The findings of this study will be presented at international conferences or published in a peer-reviewed journal.PROSPERO registration numberCRD42022384604.