Incubation period of COVID-19: a meta-analysis

Elias, Christelle; Sekri, Abel; Leblanc, Pierre; Cucherat, Michel; Vanhems, Philippe

Objectives Valid measurement of the SARS-CoV-2 incubation period is needed for case definitions and for adapting appropriate isolation measures but is challenging in an emergency context. Our objective was to systematically review recent literature of reported estimates of the distribution of incubation period of SARS-CoV-2 with the aim of describing the distribution and its variability and dispersion through meta-analysis. Methods A systematic review search was carried out up to January 10, 2021 of all identified references available reporting the SARS-CoV-2 incubation period. Individual mean and standard deviation were used to produce the pooled estimate. Sources of heterogeneity were explored by age, gender and study design using a meta-regression. Results In total, 99 studies were eligible for analysis in our meta-analysis. The pooled estimate of the mean incubation period across the studies was 6.38 days, 95% CI [5.79; 6.97]. Conclusion The mean incubation period will help for identification of time of exposure, but determinants of its variations/range might be explored for potential links with clinical outcome or pathogenic steps at early time of infection. A real time meta-analysis, called the InCoVid Lyon, is proposed on an appropriate website following this initial analysis.