Alliance for Pandemic Preparedness

February 23, 2021

Effectiveness of First Dose of COVID-19 Vaccines against Hospital Admissions in Scotland: National Prospective Cohort Study of 5.4 Million People

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[Pre-print, not peer-reviewed] A national prospective cohort study including approximately 99% of residents in Scotland (n=5.4 million) found a peak vaccine efficacy to prevent COVID-19-related hospitalization following a first dose of 85% (95% CI: 76-91%) for the Pfizer vaccine and 94% (95%CI: 73-99%) for the Oxford-AstraZeneca vaccine, with the peak occurring at 28-34 days post-vaccination. Approximately 35% of the study cohort was vaccinated. Restricting that analysis to those aged 80 or older resulted in an efficacy of 81% at 28-34 days post-vaccination. Vaccine efficacy in preventing hospitalization declined to 58% at 48 or more days post-vaccination, with the largest decline among those aged 18-64 years.

Vasileiou et al. (Feb 19, 2021). Effectiveness of First Dose of COVID-19 Vaccines against Hospital Admissions in Scotland: National Prospective Cohort Study of 5.4 Million People. Pre-print downloaded Feb 23 from https://ssrn.com/abstract=3789264