Systematic review and meta-analyses of superspreading of SARS-CoV-2 infections

Abstract

Superspreading, or overdispersion in transmission, is a feature of SARS-CoV-2 transmission which results in surging epidemics and large clusters of infection. The dispersion parameter is a statistical parameter used to characterize and quantify heterogeneity. In the context of measuring transmissibility, it is analogous to measures of superspreading potential among populations by assuming that collective offspring distribution follows a negative-binomial distribution. We conducted a systematic review and meta-analysis on globally reported dispersion parameters of SARS-CoV-2 infection. All searches were carried out on 10 September 2021 in PubMed for articles published from 1 January 2020 to 10 September 2021. Multiple estimates of the dispersion parameter have been published for 17 studies, which could be related to where and when the data were obtained, in 8 countries (e.g. China, the United States, India, Indonesia, Israel, Japan, New Zealand and Singapore). High heterogeneity was reported among the included studies. The mean estimates of dispersion parameters range from 0.06 to 2.97 over eight countries, the pooled estimate was 0.55 (95% CI: 0.30, 0.79), with changing means over countries and decreasing slightly with the increasing reproduction number. The expected proportion of cases accounting for 80% of all transmissions is 19% (95% CrI: 7, 34) globally. The study location and method were found to be important drivers for diversity in estimates of dispersion parameters. While under high potential of superspreading, larger outbreaks could still occur with the import of the COVID-19 virus by traveling even when an epidemic seems to be under control.

Keywords: COVID-19; SARS-CoV-2; dispersion parameter; meta-analysis; superspreading; systematic review.

FIGURE 1

PRISMA (Preferred Reporting Items for Systematic Reviews and Meta‐Analyses) flow diagram for the studies used to obtain studies that reported measurements of the dispersion parameter. We used PubMed for our primary search

FIGURE 2

Dispersion parameter estimates for coronavirus disease 2019 (COVID‐19) reported in 17 unique studies presented by country. (a) Estimates of dispersion parameters over countries. The error bars show the mean values and 95% confidence interval. (b) Mean estimate of dispersion parameters by countries over studies

FIGURE 3

Dispersion parameter estimates and reproduction numbers for coronavirus disease 2019 (COVID‐19) reported in 17 unique studies presented by country. The error bars show the mean values and 95% confidence interval of the dispersion parameter estimates and reported reproduction numbers in studies (Supplement). The colour denotes the estimated proportion of cases accounting for 80% of all transmissions (p _80%)

FIGURE 4

Distribution of the estimated mean dispersion parameter with respect to (a) countries studied and (b) methods studied. Black circles denote the mean estimates across studies. Vertical lines denote the mean values by averaging that for each country or method. NB: negative binomial distribution; ZT: negative binomial distribution (zero‐truncated framework); PA: phylodynamic analysis