The Impact of Prioritisation and Dosing Intervals on the Effects of COVID-19 Vaccination in Europe: An Agent-Based Cohort Model

Background: Different strategies are being explored to maximise the effect of COVID-19 vaccination in Europe. We studied the impact of different population prioritisation and dose intervals on infections, hospitalisations, mortality, and public health restrictions. Method: An agent-based model was built to quantify the impact of different vaccination strategies over 6 months. Input parameters were derived from recent phase 3 trials and official European figures. We explored the prioritisation of vulnerable people, care-home staff and residents, and contagious groups and dose intervals from 3 to 12 weeks. Findings: Prioritising vulnerable people, rather than the most contagious groups, led to higher COVID-19 prevalence, but clear reductions in mortality, hospital admissions, and restrictions. At a realistic vaccination speed of ≤0·1% population/day, separating doses by 12 (instead of 3) weeks reduced hospitalisations, mortality, and restrictions for vaccines with similar first- and second-dose efficacy (e.g., the Oxford-AstraZeneca and Moderna vaccines), but not for those with lower first-dose efficacy (e.g., the Pfizer/BioNTech vaccine). Interpretation: Mass vaccination should dramatically reduce the effect of COVID-19 on Europe’s health and economy. Early vaccination of vulnerable populations will reduce mortality, hospitalisations, and public health restrictions compared to prioritisation of the most contagious groups. The choice of interval between doses should be based on expected vaccine availability and first-dose efficacy, with 12-week intervals preferred over shorter intervals in most realistic scenarios. Funding Statement: The research was supported by the National Institute for Health Research (NIHR) Oxford Biomedical Research Centre (BRC). DPA is funded through a NIHR Senior Research Fellowship (Grant number SRF-2018-11-ST2-004). The views expressed in this publication are those of the author(s) and not necessarily those of the NHS, the National Institute for Health Research or the department of Health. CP research is partially funded by Ministerio de Ciencia e Innovacion, Gobierno de Espana through the grant PGC2018-095456-B-I00. MC is funded by La Caixa Foundation (ID 100010434), under agreement LCF/PR/GN17/50300003. Declaration of Interests: Dr. Prats reports grants from Ministerio de Ciencia e Innovacion, Gobierno de Espana (PGC2018-095456-B-I00), during the conduct of the study; other from European Commission, DG-CONNECT (CNECT/LUX/2020/LVP/0085, LC-01591965), outside the submitted work. Dr. Prieto-Alhambra reports grants and other from AMGEN, grants, non-financial support and other from UCB Biopharma, grants from Les Laboratoires Servier, outside the submitted work; and HTA Funding Committee membership. Janssen, on behalf of IMI-funded EHDEN and EMIF consortiums, and Synapse Management Partners have supported training programmes organised by DPA's department and open for external participants. Dr. CATALA reports grants from Ministerio de Ciencia e Innovacion, Gobierno de Espana (PGC2018-095456-B- I00), grants from La Caixa Foundation (ID 100010434), under agreement LCF/PR/GN17/50300003, during the conduct of the study; other from European Commission, DG-CONNECT (CNECT/LUX/2020/LVP/0085, LC-01591965), outside the submitted work. Ms. Li has nothing to disclose. Ethics Approval Statement: Only public aggregated data was used for this study. The use of such data does not require ethics approval.