Asymptomatic people with SARS-CoV-2 as unseen carriers of COVID-19: A systematic review and meta-analysis

Abstract Background The asymptomatic patients with SARS-CoV-2 can act as an unseen carrier for magnifying the transmission of COVID-19. Aims This study was designed to appraise the burden of asymptomatic individuals and estimate their occurrence among different age groups and gender by reviewing the existing published data on asymptomatic people with COVID-19. Methods Three electronic databases: PubMed, Embase and Web of Science (WoS) were used to search studies as per the guidelines of Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) and the search was limited to English language. The study population of this review includes asymptomatic individuals infected by COVID-19. All original articles which have reported cases of the COVID-19 patients with no symptoms until 31 April 2020 were included in the study. Random effects model was applied to analyze pooled data on the prevalence of symptomless cases among total COVID-19 infected patients and also on different age groups and gender. Results In the meta-analysis of 16 studies, comprising 2,788 COVID-19 infected patients, the pooled prevalence of asymptomatic cases was 48.2% (95% CI, 30%-67%). Among the asymptomatic patients, 55.5% (95% CI, 43.6%-66.8%) were female and 49.6% (95% CI, 20.5%-79.1%) were children. Conclusion About half of the COVID-19 infected patients were asymptomatic cases. Children and females were more apparent to be asymptomatic patient of COVID-19 and could act as unseen carrier of SARS-CoV-2. Symptom based screening only, might fail to identify all SARS-CoV-2 infections escalating the threat of global spread of SARS-CoV-2. Therefore, mass surveillance system tracking asymptomatic cases is a pressing need of public health, paying special attention to female and young children, which could aid in prevention and containment of this unprecedented pandemic.