Key aspects regarding the introduction and prioritisation of COVID-19 vaccination in the EU/EEA and the UK

The key components for a successful national and EU-level COVID-19 vaccine deployment are:

• a robust COVID-19 disease surveillance system;
• post-marketing studies on effectiveness and impact;
• active and passive monitoring of adverse events following immunisation;
• robust and timely vaccination coverage data;
• evidence-based decision-making;
• legal and regulatory frameworks for vaccines deployment;
• vaccine delivery infrastructure and supply chain management;
• monitoring of vaccine acceptability and behavioural research;
• communication plans;
• ethical and equitable access to vaccination.

These components are those usually adopted when a new vaccine is available on the market and integrated into national vaccination schedules.

COVID-19, caused by the virus SARS-CoV-2, is a new disease, and no vaccine is yet available for it, posing great challenges to the early development of national vaccination strategies. Patterns of exposure to SARS-CoV-2, as well as the incidence, burden and geographical distribution of COVID-19, will influence choices about vaccine deployment. There is currently a lack of certainty and knowledge about the characteristics of COVID-19 vaccines that could become available in the EU/EEA and the UK, as well as remaining gaps in the scientific knowledge of the virus and the disease. Vaccination plans and strategies will therefore need to be adapted as more information becomes available.

Once vaccines against COVID-19 are available, their supply is likely to be limited, at least initially. Supply capacity, both initially and over time, will thus determine vaccine usage and delivery prioritisation. Deployment will need to be adjusted accordingly to promptly optimise vaccine allocation and ensure vaccine availability to those most in need.

The following non-mutually exclusive approaches for vaccine deployment can be considered when building vaccination strategies, taking into account different levels of vaccine supply and stages of the pandemic:

• focusing on selected groups (e.g. individuals at risk of severe COVID-19, essential workers, vulnerable groups);
• vaccinating according to age strata (e.g. all individuals above a certain age);
• targeting groups with an increased risk of exposure and onward transmission of SARS-CoV-2 (e.g. exposure in professional settings, younger adults);
• prioritising geographical regions with high incidence of COVID-19;
• deploying the vaccine to control active outbreaks;
• performing adaptative approaches to be modulated according to circumstances;
• conducting a universal vaccination strategy.

Given the anticipated initial shortage, countries will need to identify priority groups for vaccination. A broader characterisation of these groups will need to further categorise them into different priority tiers. The identification of the priority groups, and of the tiers within them, will depend on several factors, including the disease’s epidemiology at the time of vaccine deployment, the evidence of risk of severe disease and of exposure to COVID-19, the preservation of essential societal services and equity principles, among others. In the process of developing an iterative approach for vaccine deployment with varying supply, mathematical modelling may aid public health experts in identifying priority groups for vaccination and in assessing different scenarios and the impact of alternative vaccination strategies. Lessons learned from the 2009 H1N1 influenza pandemic should also be considered.