A new statistical analysis supports the idea that Covid-19 has become more lethal in the UK at the end of 2020 and suggests that the reason is not exclusively the alpha variant of the virus, but rather that multiple factors were involved, such as a increased pressure on health care services and seasonality.
The study carried out by Patrick Pietzonka’s team from the
Cambridge University (UK), which is published in the magazine
«PLoS One», has looked at how Covid-19 lethality has changed over time in different regions for information, they write, that could help guide ongoing efforts to address this disease.
To explore if Covid-19 is
became deadlier in late 2020 in the UK, Pietzonka and his colleagues employed a statistical approach known as Bayesian inference [se trata de un tipo de inferencia estadística en la que las evidencias u observaciones se emplean para actualizar o inferir la probabilidad de que una hipótesis pueda ser cierta].
This allowed them to draw statistically stronger conclusions about fatality from weekly data on the number of cases and the number of deaths due to Covid-19 in the UK.
Specifically, they used Bayesian inference to compare the predictions of different mathematical simulations of the spread of Covid-19 and deaths, some of which incorporated higher lethality.
This analysis suggests that, in late autumn 2020 in the UK, Covid-19 was indeedand it became more lethal, which means that the probability that an infected person died from the disease increased considerably.
Previous speculation held that this increase in lethality was driven by the alpha variant (B.1.1.7) of the SARS-CoV-2 virus, which was more infectious than variants previously spread across the UK.
However, the new analysis suggests that case fatality increased to a greater degree than the alpha variant would have taken into account, and that the increased fatalityit started before the alpha variant went mainstream.
These findings suggest that while the alpha variant contributed to increased fatality in late 2020, other factors were also present.
Experts acknowledge that more research will be needed to identify these factors, but suggest they may include a increased pressure on healthcare services and seasonality, a seasonal cycle in gravity of a virus commonly seen in other respiratory diseases such as common cold and flu.