Searching for the culprit of higher COVID-19 mortality
It is natural to blame an increase in COVID-19-related deaths on the emergence of a new SARS-CoV-2 variant. The alpha variant of the virus first entered the picture in the UK in September 2020 and in just a few months became the dominant variant there and in a number of other countries worldwide. While this coincides with the increase in the virus’ lethality in late 2020, can we attribute these higher mortality rates to the alpha variant alone? A new study supported by the EU-funded ADSNeSP project provides evidence that COVID-19 became more lethal in the UK in late autumn 2020. However, based on the research’s analyses, the alpha variant was not solely to blame. Their findings are presented in a paper published in the journal ‘PLOS ONE’. The researchers investigated the possibility of a change in COVID-19 lethality in late autumn 2020 using a statistical approach called Bayesian inference. They used age-structured, weekly data on COVID-19 cases and deaths across the country to draw their conclusions and compared different models of COVID-19 spread and deaths. All of the models inferred “a close to two-fold increase” in infection fatality rate (IFR), according to the study. However, the same models also showed that “the increase in IFR preceded the time window during which variant B.1.1.7 (alpha) became the dominant strain in the UK,” suggesting that alpha is not solely to blame for the rise in deaths. “We compare these results for the UK with similar models for Germany and France, which also show increases in inferred IFR during the same period, despite the even later arrival of new variants in those countries,” the authors report.
Other culprits
So, if the alpha variant is not the only culprit, what else is to blame for the dramatic rise in COVID-related deaths in the UK during this period? According to the authors, other factors, such as seasonality and/or pressure on health services are also likely to have contributed to the change. “Of these, seasonality more credibly would have had similar effects in the UK and Germany (and perhaps weaker effects in France, but this is far from clear),” they write. “This conclusion may also be supported by a study from Israel addressing changes of in-hospital mortality rates.” The authors would like to see if their evidence persists as more recent data and other types of observations are added to the models: “This might include data for hospital admissions, antibody testing, or random asymptomatic testing (as already considered a posteriori in this report). More data would also enable more detailed versions of our models to be constructed. For example, we have neglected so far the possibility of reinfection (loss of immunity). It would be also possible to represent more accurately the timing of the progression through stages of infection. Large-scale vaccination campaigns may also be accounted for in future variants of these models.” ADSNeSP (Active and Driven Systems: Nonequilibrium Statistical Physics) is coordinated by the University of Cambridge. The project ends in September 2022. For more information, please see: ADSNeSP project
Keywords
ADSNeSP, coronavirus, COVID-19, SARS-CoV-2, variant, alpha, alpha variant, death, mortality, United Kingdom
