Abstract
Asymptomatic cases of SARS-CoV-2 can be unknown carriers magnifying the transmission of COVID-19. This study appraised the frequency of asymptomatic individuals and estimated occurrence by age group and gender by reviewing the existing published data on asymptomatic people with COVID-19. Three electronic databases, PubMed, Embase, and Web of Science (WoS), were used to search the literature following the guidelines of Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA). The study population for this review included asymptomatic individuals infected with SARS-CoV-2 reported in original articles published up to 30 April 2020. A random effects model was applied to analyze pooled data on the prevalence of asymptomatic cases among all COVID-19 patients and also by age and gender. From the meta-analysis of 16 studies, comprising 2,788 SARS-CoV-2 infected patients, the pooled prevalence according to the random effect size of asymptomatic cases was 48.2% (95% CI, 30–67%). Of the asymptomatic cases, 55.5% (95% CI, 43.6–66.8%) were female and 49.6% (95% CI, 20.5–79.1%) were children. Children and females were more likely to present as asymptomatic COVID-19 cases and could act as unknown carriers of SARS-CoV-2. Symptom-based screening might fail to identify all SARS-CoV-2 infections escalating the threat of global spread and impeding containment. Therefore, a mass surveillance system to track asymptomatic cases is critical, with special attention to females and children.
Highlights
Coronaviruses are common respiratory pathogens causing illness in humans around the world [1]
SARS-CoV-2 was identified as the seventh virus of the coronaviridae family causing infection to humans and the World Health Organization (WHO) announced “COVID-19” as a new disease on 11 February 2020 [4]
Most studies were from China (n = 11), two were from Japan and three were from the United States of America (USA), with a total of 2,788 SARS-CoV-2 infected patients (Table 1)
Summary
Coronaviruses are common respiratory pathogens causing illness in humans around the world [1]. By the end of 2019, six different coronaviruses contagious to humans had been reported [2, 3]. SARS-CoV-2 was identified as the seventh virus of the coronaviridae family causing infection to humans and the World Health Organization (WHO) announced “COVID-19” as a new disease on 11 February 2020 [4]. In response to the rapid global spread of SARS-CoV-2, WHO declared COVID-19 as a Public Health Emergency of International Concern (PHEIC) on 30 January 2020 and a pandemic on 11 March 2020 [5]. As of 26 May 2020, there were 5,508,904 confirmed cases of COVID-19 with 346,612 deaths globally [6]
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