How do adherence to COVID-19 mitigation measures and its predictors change between 2020 and 2021?

\(\bf Introduction:\) Adherence to COVID-19 mitigation measures is an important vehicle that has contributed to the fight against the pandemic. The present study investigated potential changes of the level of adherence and its predictors between 2020 and 2021 in eight countries. \(\bf Methods:\) Adherence to COVID-19 measures and its potential predictors (perception of usefulness of the measures, rating of the governmental COVID-19 communication, mental health variables, COVID-19 burden) were compared between representative population samples from European Union countries (France, Germany, Poland, Spain, Sweden) and non-European Union countries (Russia, UK, USA) assessed in 2020 (\(\it N\) = 7,658) and 2021 (\(\it N\) = 8,244). \(\bf Results:\) In the overall sample, multiple analyses of variance revealed significantly higher levels of adherence to the measures, their perception as useful, positive mental health, and feelings of being well supported and well informed by governments in 2020 than in 2021. In contrast, feelings of being left alone and symptoms of depression, anxiety, and stress were significantly higher in 2021 than in 2020. In France, Poland, Spain, and the UK, the adherence level was significantly higher in 2020 than in 2021. In European Union countries, ratings of governmental communication were less positive, and levels of mental health were lower in 2021 than in 2020. In non-European countries, an opposite result pattern was found. \(\bf Conclusion:\) The current results indicate a decrease in adherence to the mitigation measures and factors that could foster it. Potential ways how governments and authorities could enhance the population’s trust in COVID-19 mitigation measures are discussed.