Impact of Vaccination on COVID-19 case fatality in the United Kingdom

We examined trends and differences in the number of COVID-19 cases and deaths and corresponding estimates of case fatality in the United Kingdom (UK) during the 20-month period, 3/1/2020-10/31/2021. Three distinct stages of the epidemic in the UK population of 68.4 million were noted corresponding to successive surges in the number of cases and deaths. For these three successive time periods, crude case fatality rates (case fatality = number of deaths / number of cases) fell dramatically: 12.4% during the early months of the epidemic, (335,210 cases and 41,564 deaths during 3/1-8/31/2020), 2.08% during the autumn, winter and spring months of 2020 and 2021 (4,148,076 cases and 86,254 deaths during 9/1/2020-5/31/2021), and 0.28% during the summer and autumn months of 2021 (4,573,571 cases and 12,814 deaths during 6/1-10/31, 2021). A high proportion (80-90%) of the UK population was vaccinated against SARS CoV-2 during the latter stage when the dominant infection was due to the Delta variant of SARS CoV-2. Results suggest that COVID-19 vaccines did not prevent viral transmission in the UK but were associated with a marked reduction in case fatality.