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

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.

SARS-CoV-2 Delta VOC in Scotland: demographics, risk of hospital admission, and vaccine effectiveness

“…EAVE II is a Scotland-wide COVID-19 surveillance platform that has been used to track and forecast the epidemiology of COVID-19, inform risk stratification, and investigate vaccine effectiveness and safety. 1 , 2 , 3 , 4 It comprises national health-care datasets on 5·4 million people (about 99% of the Scottish population) linked through Scotland's unique Community Health Index number.…”

“…Building on methods that have previously been described in detail, we defined a COVID-19 hospital admission as being within 14 days of testing positive for SARS-CoV-2. 3 , 5 Individuals who tested positive within 2 days after a hospital admission were also included. Individuals tested during a hospital stay from day 3 onwards were excluded.…”

Socially optimal pandemic drug dosing

“…Although insufficient selective pressure due to a lower dose theoretically increases the likelihood that a resistant viral strain emerges, so too does actively choosing not to maximise vaccine availability. 9 Real-world data support an activist approach to vaccine dosing 4 , 5 and, to our knowledge, no vaccine-resistant strains have emerged in the UK. We all must acknowledge that even in the best of pandemic circumstances—infinite vaccine supply allowing for strict adherence to dosing guidance from randomised controlled trials—the emergence of a vaccine-resistant viral strain is a known unknown.…”

“…Similarly, the best available evidence for extending the interval between doses of mRNA vaccines comes from (overwhelmingly successful) calculated risk-taking in the UK. 4 , 5 Early attention to dose and timing strategies would have facilitated population vaccination strategies and benefited those tasked with crafting policy.…”

Impfung gegen SARS-CoV-2 bei Krebspatienten

“…Dabei zeigte sich im schottischen Register mit 5,4 Mio. Personen bereits nach der ersten Schutzimpfung mit der AstraZeneca-Vakzine ein Rückgang in der COVID-19-bezogenen Hospitalisationsrate um 95 % [ 17 ].…”