First-Dose Mass COVID-19 Vaccination and COVID-19 Hospital Admissions

Quick Takes

  • This is the first population-level study reporting on the incidence of hospitalizations for COVID-19 in relation to the mass vaccination campaign for COVID-19 in Scotland.
  • Both BNT162b2 mRNA and ChAdOx1 vaccines were associated with significant decreases in the relative risk of hospitalization for COVID-19.
  • Vaccine uptake was lower in men, people of lower socioeconomic status, and those living in large urban areas.

Study Questions:

Is mass vaccination for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) associated with a reduction in hospitalizations for coronavirus disease 2019 (COVID-19)?

Methods:

The investigators leveraged Scotland’s Early Pandemic Evaluation and Enhanced Surveillance of COVID-19—EAVE II—database comprising linked vaccination, primary care, real-time reverse transcription-polymerase chain reaction testing, and hospital admission patient records to determine whether mass vaccination for SARS-CoV-2 using either the BNT162b2 mRNA or ChAdOx1 vaccines were associated with a decrease in hospital admission for COVID-19. The database comprises information on 5.4 million people (99% of the population of Scotland). Individuals who previously tested positive were excluded from the analysis. The primary outcome was the rate of hospitalization for COVID-19 after the first vaccine dose.

Results:

Between December 8, 2020, and February 22, 2021, a total of 1,331,993 people were vaccinated (mean age 65 years, 40% male, 28% having ≥2 comorbidities). Vaccine uptake was higher for women compared to men (35% vs. 25%) and for those with a higher number of comorbidities. The effectiveness of the vaccines ranged from 53% to 97% depending on the post-vaccine time range examined. The first dose of the BNT162b2 mRNA vaccine was associated with a vaccine effect of 91% (95% confidence interval [CI], 85–94) for reduced COVID-19 hospital admission at 28–34 days post-vaccination. In those aged ≥80 years, the pooled analysis for both vaccines showed an effect of 83% (95% CI, 72-89).

Conclusions:

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.

Perspective:

This first population-level study reporting on the association between mass vaccination and hospitalization for COVID-19 confirms the effectiveness of the BNT162b2 mRNA and ChAdOx1 vaccines in a real-world setting, and across age groups. The primary outcome of the study was hospitalization for COVID-19; which did not account for potential outpatient or emergency department COVID-19 diagnoses. Dissecting the impact of the lockdowns in Scotland from that of the vaccination campaigns is also challenging and may also lead to overestimation of the effectiveness of the vaccines. The study also did not account for the second vaccination dose, given an insufficient number of patients had received it by the time the study was complete. Nevertheless, the findings are confirmatory and reassuring.

Clinical Topics: Geriatric Cardiology, Prevention

Keywords: Comorbidity, Coronavirus, COVID-19, Geriatrics, Mass Vaccination, Outpatients, Polymerase Chain Reaction, Primary Health Care, Primary Prevention, Risk, RNA, Messenger, SARS-CoV-2, Vaccination


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