The different variants are not the only ones responsible for this increase in the lethality of the virus.
- In France, the virus has claimed more than 118,000 lives.
- The Alpha variant was first observed in England in December 2020.
More than 140,000 people have died of Covid-19 in the UK. Data collected since the start of the pandemic suggests that virus-related mortality has increased in the country, without scientific analyzes being carried out. Researchers from the University of Cambridge wanted to confirm this hypothesis using reliable statistical tools. Their results are published in PLOS ONE.
A statistically confirmed increase in lethality
To achieve this, Patrick Pietzonka, lead author of this research, and his team used the method of Bayesian inference. This algorithmic technique makes it possible to determine the level of confidence that can be granted to a hypothesis. This allowed them to draw statistically stronger conclusions about lethality from weekly data on the number of cases and the number of deaths from Covid-19 in the UK. According to the scientists’ conclusions, the new coronavirus has indeed become more deadly from the end of autumn 2020 in the United Kingdom, concretely, this means that the probability that an infected person will die from the disease has increased.
Why has the virus become more deadly?
Previous hypotheses suggested that this increase in lethality was the consequence of the new variant, says Alpha (B.1.1.7). It has been shown to be more contagious than other mutations previously identified in the UK. Last March, scientists proved that the Alpha variant was more deadly than the strain”classicof the virus: on average, its lethality rate is 64% higher. But according to researchers from the University of Cambridge, the increase in lethality has been to an excessively high degree, which cannot be explained solely by the Alpha variant. On the other hand, this increase was observed before this variant became widespread. This means that other factors contributed to aggravate the lethality of the virus. For the authors, there are several hypotheses: the increased pressure on health services could be a potential explanation, but it could also be due to seasonality, as there is a seasonal cycle in the severity of a virus, commonly seen for other respiratory illnesses such as colds and flu. For the authors of this study, better understanding the lethality of Covid-19 and the reasons for its increase makes it possible to participate in “continuous efforts to fight this disease”.
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