Statistical analysis
Individual mean and standard deviation were used to produce the pooled estimate. In absence of reporting of standard deviation, we recalculate it from confidence interval limits if available, or from the 1st and 3rd quartiles or from the range using approximation formula [5]. Inverse variance weighting was used for pooling individual estimation of mean, 95th end 97.5th percentile of the incubation period. A random-effects model was used. Heterogeneity between studies was assessed using I2 statistics, with an I2 of more than 50% indicating substantial heterogeneity [6]. We explored sources of heterogeneity with a meta-regression for continuous explicative covariables and by subgroup analysis for qualitative explicative covariables. Age, gender and study design were considered as candidate explicative covariables. All data analyses were done using R (version 3.6.3) with R package meta and the metamean function. Results of this real-time meta-analysis are shared on the following site: InCoVid-Lyon [7].