Incubation period of SARS-CoV-2: A systematic review and meta-analysis

Wassie, Gizachew Tadesse; Azene, Abebaw Gedef; Bantie, Getasew Mulat; Dessie, Getenet; Aragaw, Abiba Mihret

Background: Coronavirus disease (COVID-19) has currently become a major global public health problem. The prevalence of COVID-19 has increased rapidly worldwide. Since there is no effective COVID-19 vaccine available yet, it is increasingly important to understand the average incubation period of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) to design appropriate preventive and control strategies. Therefore, this systematic review and meta-analysis was designed to estimate the pooled average incubation period of SARS-CoV-2. Methods: We conducted a systematic electronic web-based search of online databases including PubMed, Google Scholar, EMBASE, and the World Health Organization's HINARI portal. We included peer-reviewed research studies written in the English language on the incubation period of SARS-CoV-2 using pre-defined quality and inclusion criteria. STATA version 15 statistical software was used to analyze the data. Joanna Briggs Institute (JBI) critical appraisal quality assessment tool for observational studies was utilized to evaluate the included studies. We extracted relevant data and presented in a tabular form. The I(2) test was used to assess heterogeneity across studies. Funnel plot asymmetry and Egger's tests were used to check for publication bias. The final effect size was determined by applying a random-effects model. Results: Our search identified 206 studies, amongst which 18 studies, representing 22,595 participants were included in the final analysis. The pooled average incubation period of SARS-CoV-2 was 5.7 days (95% CI: 5.1, 6.4). Subgroup analyses by geographic location showed that the pooled average incubation period of SARS-CoV-2 was 6.1 days (95% CI: 5.34, 6.94) in China and 4.54 (95% CI: 3.9, 5.2) in other countries (Singapore, South Korea, and globally). Conclusion: The pooled average incubation period of SARS-CoV-2 was about six days. The longest incubation period was observed in China. The global health initiatives as well as local health planners should consider, this average incubation period while designing optimal prevention and control strategies for SARS-CoV-2.