Interim findings from first-dose mass COVID-19 vaccination roll-out and COVID-19 hospital admissions in Scotland : a national prospective cohort study

Vasileiou, Eleftheria and Simpson, Colin R and Shi, Ting and Kerr, Steven and Agrawal, Utkarsh and Akbari, Ashley and Bedston, Stuart and Beggs, Jillian and Bradley, Declan and Chuter, Antony and de Lusignan, Simon and Docherty, Annemarie B and Ford, David and Hobbs, FD Richard and Joy, Mark and Katikireddi, Srinivasa Vittal and Marple, James and McCowan, Colin and McGagh, Dylan and McMenamin, Jim and Moore, Emily and Murray, Josephine LK and Pan, Jiafeng and Ritchie, Lewis and Shah, Syed Ahmar and Stock, Sarah and Torabi, Fatemeh and Tsang, Ruby SM and Wood, Rachael and Woolhouse, Mark and Robertson, Chris and Sheikh, Aziz (2021) Interim findings from first-dose mass COVID-19 vaccination roll-out and COVID-19 hospital admissions in Scotland : a national prospective cohort study. The Lancet, 397 (10285). pp. 1646-1657. ISSN 0140-6736 (https://doi.org/10.1016/S0140-6736(21)00677-2)

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Abstract

Background: The BNT162b2 mRNA (Pfizer–BioNTech) and ChAdOx1 nCoV-19 (Oxford–AstraZeneca) COVID-19 vaccines have shown high efficacy against disease in phase 3 clinical trials and are now being used in national vaccination programmes in the UK and several other countries. Studying the real-world effects of these vaccines is an urgent requirement. The aim of our study was to investigate the association between the mass roll-out of the first doses of these COVID-19 vaccines and hospital admissions for COVID-19. Methods: We did a prospective cohort study using the Early Pandemic Evaluation and Enhanced Surveillance of COVID-19—EAVE II—database comprising linked vaccination, primary care, real-time reverse transcription-PCR testing, and hospital admission patient records for 5·4 million people in Scotland (about 99% of the population) registered at 940 general practices. Individuals who had previously tested positive were excluded from the analysis. A time-dependent Cox model and Poisson regression models with inverse propensity weights were fitted to estimate effectiveness against COVID-19 hospital admission (defined as 1–adjusted rate ratio) following the first dose of vaccine. Findings: Between Dec 8, 2020, and Feb 22, 2021, a total of 1 331 993 people were vaccinated over the study period. The mean age of those vaccinated was 65·0 years (SD 16·2). The first dose of the BNT162b2 mRNA vaccine was associated with a vaccine effect of 91% (95% CI 85–94) for reduced COVID-19 hospital admission at 28–34 days post-vaccination. Vaccine effect at the same time interval for the ChAdOx1 vaccine was 88% (95% CI 75–94). Results of combined vaccine effects against hospital admission due to COVID-19 were similar when restricting the analysis to those aged 80 years and older (83%, 95% CI 72–89 at 28–34 days post-vaccination). Interpretation: Mass roll-out of the first doses of the BNT162b2 mRNA and ChAdOx1 vaccines was associated with substantial reductions in the risk of hospital admission due to COVID-19 in Scotland. There remains the possibility that some of the observed effects might have been due to residual confounding. Funding: UK Research and Innovation (Medical Research Council), Research and Innovation Industrial Strategy Challenge Fund, Health Data Research UK.

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