BNT162b2 and ChAdOx1 nCoV-19 vaccinations, incidence of SARS-CoV-2 infections and COVID-19 hospitalisations in Scotland in the Delta era

Funding: EAVE II is supported by the Medical Research Council (MR/R008345/1) with the support of BREATHE – The Health Data Research Hub for Respiratory Health, which is funded through the UK Research and Innovation Industrial Strategy Challenge Fund [MC_PC_19004] and delivered through Health Data Research UK. Additional support has been provided through Public Health Scotland and Scottish Government DG Health and Social Care, the Data and Connectivity National Core Study, led by Health Data Research UK in partnership with the Office for National Statistics and funded by UK Research and Innovation (grant ref MC_PC_20058;) and the Lifelong Health and Well-being study as part of the National Core Studies (MC_PC_20030).The emergence of the B.1.617.2 Delta variant of concern was associated with increasing numbers of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections and COVID-19 hospital admissions. We aim to study national population level SARS-CoV-2 infections and COVID-19 associated hospitalisations by vaccination status to provide insight into the association of vaccination on temporal trends during the time in which the SARS-CoV-2 Delta variant became dominant in Scotland. We used the Scotland-wide Early Pandemic Evaluation and Enhanced Surveillance (EAVE II) platform, covering the period when Delta was pervasive (May 01 to October 23, 2021). We performed a cohort analysis of every vaccine-eligible individual aged 20 or over from across Scotland. We determined the vaccination coverage, SARS-CoV-2 incidence rate and COVID-19 associated hospitalisations incidence rate. We then stratified those rates by age group, vaccination status (defined as "unvaccinated", "partially vaccinated" (1 dose), or "fully vaccinated" (2 doses)), vaccine type (BNT162b2 or ChAdOx1 nCoV-19), and coexisting conditions known to be associated with severe COVID-19 outcomes. During the follow-up of 4 183 022 individuals, there were 407 405 SARS-CoV-2 positive cases with 10 441 (2.6%) associated with a hospital admission. Those vaccinated with two doses (defined as fully vaccinated in the current study) of either vaccine had lower incidence rates of SARS-CoV-2 infections and much lower incidence rates of COVID-19 associated hospitalisations than those unvaccinated in the Delta era in Scotland. Younger age groups were substantially more likely to get infected. In contrast, older age groups were much more likely to be hospitalised. The incidence rates stratified by coexisting conditions were broadly comparable with the overall age group patterns. This study suggests that national population level vaccination was associated with a reduction in SARS-CoV-2 infections and COVID-19 associated hospitalisation in Scotland throughout the Delta era.Publisher PDFPeer reviewe