Estimation of country-level basic reproductive ratios for novel Coronavirus (COVID-19) using synthetic contact matrices

Joe Hilton; Matt J Keeling

is the (which was not peer-reviewed) The copyright holder for this preprint . core-group within the population. For COVID-19, this means that we see higher scaling factors in countries with older populations, since this usually means contacts involving older individuals are more common. In countries with comparitively younger populations, contacts involving older individuals are less common and so the capacity of the infection to spread is reduced relative to the purely-contact pattern based transmission model. Figure 3 (b) illustrates this principle for Niger (which is predicted to have one of the lowest scalings of the reproductive ratio) and Poland (which is predicted to have one of the highest scalings) in comparison to China. The population pryamid of Niger is dominated by young children; China has a relatively stable agestructure although there are more individuals in 30-54 age classes than in younger age-groups; the pryamid for Poland shows even fewer children and substantial proportions into older age-classes. We therefore observe 5 . CC-BY-NC-ND 4.0 International license It is made available under a author/funder, who has granted medRxiv a license to display the preprint in perpetuity.