Potentially Asymptomatic Infection of Monkeypox Virus: A Systematic Review and Meta-Analysis

Background: Monkeypox is a global public health concern, given the recent outbreaks in non-endemic countries where little scientific evidence exists on the disease. Specifically, there is a lack of data on asymptomatic monkeypox virus infection. This study aims to evaluate the overall prevalence of asymptomatic monkeypox virus infection. Methods: In this systematic review and meta-analysis, we performed an extensive literature search in PubMed, Scopus, Web of Science, ProQuest, EMBASE, EBSCOHost, Cochrane, and preprint servers (medRxiv, arXiv, bioRxiv, BioRN, ChiRxiv, ChiRN, and SSRN) and assessed all published articles till September 2022. Primary studies reporting monkeypox infections among asymptomatic participants were included after quality assessment. The characteristics of the study and information on the number of cases and symptomatic status were extracted from the included studies. The heterogeneity between studies was assessed using the I² statistic. Publication bias was analyzed using funnel plots and Egger regression tests. The primary outcome was the pooled prevalence of asymptomatic infections within the examined population. Results: A total of 16 studies were included for qualitative synthesis, while five studies, including 645 individuals, were included for quantitative synthesis. There was substantial heterogeneity between studies (I² = 94.86%; p < 0.01), with a pooled percentage of asymptomatic infections in the studied population of 10.2% (95%CI, 2.5–17.9%). Conclusion: This meta-analysis suggests that many people infected with the monkeypox virus are asymptomatic and difficult to detect. Therefore, prompt detection of these cases of monkeypox virus and appropriate subsequent management is of utmost importance to global public health.