Abrupt increase in the UK coronavirus death-case ratio in December 2020

1Objectiveto determine the statistical relationship between reported deaths and infections in the UK coronavirus outbreak DesignPublicly available UK government data is used to determine a relationship between reported cases and deaths, taking into account various UK regions, age profiles and prevalence of the variant of concern (VOC) B.1.1.7. Main Outcome MeasuresEstablishing a simple statistical relationship between detected cases and subsequent mortality. ResultsThroughout October and November 2020, deaths in England are well described as 1/55th of detected cases from 12 days previously. After that, the relationship no longer holds and deaths are significantly higher. This is especially true in regions affected by the VOC B.1.1.7 ConclusionsIn early December, some new factor emerged to increase the case-fatality rate in the UK. Summary BoxO_ST_ABSWhat is already known on this topicC_ST_ABSThe infection-mortality ratio enables one to predict future deaths based on current infections. Incomplete monitoring of infection may be sufficient to predict future trends. What the study addsFor the specific case of the second wave of coronavirus infection in the UK, we show a clear mathematical relationship between detected infections (positive tests) and subsequent deaths. This relationship begins to fail in December, with unexpectedly high death rates. This may be correlated in time and region with the emergence of the Variant of Concern B 1.1.7.