Tracking the evolution of the lethality of the COVID-19 disease over time in different regions of a country or the world is essential for targeting efforts to control the disease. Initial analyzes of infection and mortality data suggested that the disease would have become more deadly in the United Kingdom at the end of 2020, this analysis, more rigorous, specifies this evolution and its main factors.
–
A statistical approach that allows to model lethality
The team developed a ‘Bayesian inference’ type statistical approach that allowed them to draw statistically sound conclusions about lethality from weekly data of the number of COVID-19 cases and the number of COVID-19 deaths in the UK. The model suggests that in late autumn 2020 in the UK,
- COVID-19 has indeed become more deadly (an infected person then has a higher risk of death).
- the emergence of the alpha variant (B.1.1.7) of the SARS-CoV-2 virus, which is more contagious than the variants previously circulating in the United Kingdom, is confirmed as one of the factors increasing the lethality;
- however, lethality increased to a level greater than the effect of the alpha variant alone and this increased lethality began long before its circulation was generalized;
What other factors for this increase in lethality? The authors evoke, without demonstrating it, the effect of the increased pressure of the pandemic on health services as well as the seasonality of the virus which could also influence its virulence, as is the case for other respiratory diseases such as colds and flu.
An analysis with some limitations, while the authors take little account of the considerable progress in the progress made since, in vaccination as well as in the management and treatment protocols.
–
