Demographic science aids in understanding the spread and fatality rates of COVID-19

Jennifer Beam Dowd; Valentina Rotondi; Liliana Adriano; David M Brazel; Per Block; Xuejie Ding; Yan Liu; Melinda C Mills

In Figure 1 , we use population pyramids to illustrate how population age structure interacts with high COVID-19 mortality rates at older ages to generate large differences across populations in the number of deaths, using existing assumptions about infection prevalence and age-specific mortality. The top panel considers two countries currently affected, Italy and South Korea. The larger number of expected fatalities for Italy is clearly visible in the right panel. In the bottom panel, we consider two countries yet untouched by the pandemic who have similar population sizes but very different age distributions. In Brazil, which has 2.0% of its population age 80+, the simulated scenario leads dramatically more deaths (1,025,341) compared to Nigeria (300,715), where the fraction over 80 is only 0.2%. Figure 2 uses an alternative visualization to depict the expected deaths by age groups in Italy, Brazil, Nigeria, UK and US, together with the proportion of the population in different age groups. Both figures demonstrate the stark implications of an older population age structure for higher fatalities and critical cases.