Mathematical analysis of COVID mortality rates in the United States and Europe shows that second-wave mortality was often greatly reduced — particularly in wealthier European countries and the northeast of the U.S.

Researchers say mortality change could have several explanations:

• European first-wave case counts were underestimated;
• First-wave deaths disproportionately affected the elderly;
• Second-wave infections tended to affect younger people;
• With some exceptions, lower mortality rates occurred in countries with more socialised and equitable health systems.

The researchers, Nick James, Max Menzies and Peter Radchenko, believe their new methodology could assist epidemiologists to analyse data consistently to assess the impact of COVID-19 mortality across populations.

«We have been able to look at the mortality rates in a more dynamic way,» said Mr James from the University of Sydney.

They have published their results today in the mathematical journal Chaos.

«We take a time series of infection rates by country, apply an algorithmic approach to chop it up into first and later waves and then do some relatively simple optimisation and calculations to determine two different mortality numbers,» said Nick James, a PhD student in the School of Mathematics & Statistics at the University of Sydney.

Story Source: Materials provided by University of Sydney. Note: Content may be edited for style and length.