Potential impact of the UK vaccination strategy on the numbers of patients becoming critically ill with COVID-19
Authors: Harrison David , Gould Doug , Rowan Kathryn 
Published: February 2021

ObjectivesWith the aim of shifting the emphasis from mortality to pressure on the NHS, we, first, mapped the nine priority groups outlined by the Joint Committee on Vaccination and Immunisation (JCVI) for Phase 1 of the vaccination strategy to available critical care data fields in the ICNARC COVID-19 study. Second, we examined the likely impact of vaccinating these priority groups on the numbers of patients becoming critically ill with COVID-19. Third, we described the characteristics of the critically ill patients with confirmed COVID-19 not covered by the Phase 1 priority groups for vaccination with a view to informing groupings for Phase 2 of the vaccination strategy. MethodsPhase 1 priority groups for vaccination were those identified by the JCVI. Data fields on patient characteristics, available from the ICNARC COVID-19 study built on the Case Mix Programme - the national clinical audit for adult critical care, were mapped to each of the nine priority groups. General population estimates, by age and sex for England, Wales and Northern Ireland combined, were obtained from the Office for National Statistics. The number and percentage of patients covered by the Phase 1 priority groups were calculated, applying the mapped ICNARC COVID-19 study data fields, using data on patients critically ill with confirmed COVID-19 from 1 February 2020 to 31 January 2021. The characteristics of patients not covered by the Phase 1 priority groups were reported as numbers and percentages and, where possible, as rates per one million general population.ResultsOf the 12 groups/subgroups (derived from the nine Phase 1 priority groups), eight mapped precisely. Of the remaining four, two were unable to be mapped due to absence of occupation data fields in the ICNARC COVID-19 study and two were partially mapped. Between 1 February 2020 and 31 January 2021, there were a total of 31,489 patients critically ill with confirmed COVID-19. Applying the data on the characteristics of these patients to the mapped Phase 1 priority groups, 26,628 (84.6%) were covered. For priority groups 1-4, 8,811 (28%) were covered.Of the 4,861 (15.4%) patients critically ill with confirmed COVID-19 not covered, older age groups and male sex dominated with two-thirds 40 years or older and two-thirds male. Per one million general population, the disparity between males and females increased with increasing age. Almost half were from non-White ethnic groups with one quarter of these categorised as Asian. Almost 60% resided in areas of greater deprivation with over 90% residing in urban environments.ConclusionOur mapping suggests that Phase 1 of the vaccination strategy has the potential to impact the numbers of patients becoming critically ill with COVID-19, substantially. Among those not covered by the nine Phase 1 priority groups, age remains a dominant factor, however, males and some ethnic groups appear disproportionally represented. Given the current and recent overwhelming burden of COVID-19 on critical care services in the NHS, our estimates for a substantial reduction in the numbers of patients becoming critically ill with COVID-19 will be welcome news.