february 2021 • Pre Print

Effectiveness of first dose of COVID-19 vaccines against hospital admissions in Scotland: national prospective cohort study of 5.4 million people

Vasileiou V., et al

Content curated by:David Rodrigues

Key message

Estudo de base populacional com 5.4 milhões de escoceses em que usam bases de dados interligadas para fazer corresponder dados de vacinação com dados hospitalares. A primeira dose da vacina BNT162b2 foi associada a uma redução de 85% (intervalo de confiança de 95% [IC] 76 a 91) para hospitalização relacionada a COVID-19 28-34 dias após a vacinação. No mesmo intervalo de tempo para a vacina ChAdOx1 o efeito foi de 94% (IC 95% 73 a 99). Os resultados do efeito da vacina combinada para a prevenção de hospitalização relacionada a COVID-19 foram comparáveis ao restringir a análise àqueles com idade ≥80 anos (81%; IC 95% 65 a 90 em 28-34 dias após a vacinação).

Analysis

Population

Adultos vacinados para covid-19

Method

Coorte de base populacional

Results

Decréscimo na taxa de hospitalização a 28-34 dias por covid-19 nas pessoas vacinadas para covid-19 com a vacina Pfizer-BioNTech de 85% (intervalo de confiança de 95% [IC] 76 a 91) e, no mesmo intervalo de tempo para a vacina ChAdOx1, de 94% (IC 95% 73 a 99).

Abstract

Background: The BNT162b2 mRNA (Pfizer-BioNTech) and ChAdOx1 (Oxford- AstraZeneca) COVID-19 vaccines have demonstrated high efficacy against infection in phase 3 clinical trials and are now being used in national vaccination programmes in the UK and several other countries. There is an urgent need to study the ‘real-world’ effects of these vaccines. The aim of our study was to estimate the effectiveness of the first dose of these COVID-19 vaccines in preventing hospital admissions. Methods: We conducted a prospective cohort study using the Early Pandemic Evaluation and Enhanced Surveillance of COVID-19 (EAVE II) database comprising of linked vaccination, primary care, Real-Time Polymerase Chain Reaction (RT-PCR) testing, hospitalisation and mortality records for 5.4 million people in Scotland (covering ~99% of population). A time- dependent Cox model and Poisson regression models were fitted to estimate effectiveness against COVID-19 related hospitalisation (defined as 1- Adjusted Hazard Ratio) following the first dose of vaccine. Findings: The first dose of the BNT162b2 vaccine was associated with a vaccine effect of 85% (95% confidence interval [CI] 76 to 91) for COVID-19 related hospitalisation at 28-34 days post-vaccination. Vaccine effect at the same time interval for the ChAdOx1 vaccine was 94% (95% CI 73 to 99). Results of combined vaccine effect for prevention of COVID-19 related hospitalisation were comparable when restricting the analysis to those aged ≥80 years (81%; 95% CI 65 to 90 at 28-34 days post-vaccination). Interpretation: A single dose of the BNT162b2 mRNA and ChAdOx1 vaccines resulted in substantial reductions in the risk of COVID-19 related hospitalisation in Scotland. Funding: UK Research and Innovation (Medical Research Council); Research and Innovation Industrial Strategy Challenge Fund; Health Data Research UK.