An Overview of Strategies to Improve Vaccination Compliance before and during the COVID-19 Pandemic.

The debate on vaccination mandate was fuelled over the past two years by the COVID-19 pandemic. This study aimed at overviewing vaccination strategies and corresponding vaccine coverages for childhood vaccinations before the pandemic and for SARS-CoV-2 in high-income countries. A qualitative comparison was also performed between the two contexts: unlike for childhood vaccinations, only one European country (Austria) imposed generalised COVID-19 mandates, most countries preferring targeted mandates for higher-risk categories (Italy, Greece) or workers in key public services (Finland, Australia, New Zealand, UK, Germany). Many countries (Norway, Sweden, Netherlands, Portugal, Spain) confirmed their traditional voluntary vaccination approach also for COVID-19, while others (Slovenia and Hungary), historically relying on compulsory vaccination strategies, surprisingly opted for voluntary SARS-CoV-2 vaccination, with unsatisfactory results in terms of immunisation rates. However, no tangible relationship was generally found between vaccination policies and immunisation coverages: data show that, unlike some countries with mandates, countries where vaccinations are merely recommended could achieve higher coverages, even beyond the recommended 95% threshold. The COVID-19 experience has enriched pre-existent vaccination strategy debates by adding interesting elements concerning attitudes towards vaccines in a novel and unexplored context. Interpreting the available results by considering the different cultural contexts and vaccine hesitancy determinants can help to better understand the complexity of the relationship between policies and achieved coverages.