Willingness to receive an annual COVID-19 booster vaccine in the German-speaking D-A-CH region in Europe: A cross-sectional study

Background: Emergence of new coronavirus variants and waning immunity may necessitate regular COVID-19 vaccine boosters, but empirical data on population willingness for regular vaccination are limited. Methods: In August 2021, we surveyed 3,067 quota-sampled German-speaking adults residing in the D-A-CH region (Germany, Austria, Switzerland). Using multivariable adjusted ordered logistic regression models we calculated odds ratios (OR) and 95% confidence intervals (95% CIs) to assess factors associated with willingness to vaccinate annually against COVID-19. Findings: Among 2,480 participants vaccinated or planning to get vaccinated, 82·4% indicated willingness to receive annual COVID-19 boosters. This willingness was higher in Austria (OR=1·47, 95% CI, 1·19–1·82; p < 0·001) and Germany (OR=1·98, 95% CI, 1·60–2·45; p < 0·001) versus Switzerland and increased with age. Having voted in the last national election (OR_{opposition party voters}=1·51, 95% CI=1·18–1·92; p = 0·001 and OR_{governing party voters}=1·57, 95% CI=1·28–1·93; p < 0·001, versus non-voters) and not regularly participating in religious meetings (OR=1·37, 95% CI=1·08–1·73; p = 0·009, versus participation at least monthly) were significantly associated with willingness to vaccinate, as was partial (OR=1·97, 95% CI=1·43–2·72; p < 0·001) or total (OR=5·20, 95% CI=3·76–7·19; p < 0·001) approval of COVID-19 mitigation measures (versus non-approval). By country, Austrians showed the strongest association of voting behavior and mitigation measure approval with willingness to vaccinate. Interpretation: Targeted promotion programs informed by political and religious engagement and mitigation measure approval are needed to increase willingness to receive regular COVID-19 boosters. Funding: Medical University of Vienna, Department of Epidemiology, Danube University Krems, Department for Knowledge and Communication Management; Austrian Society of Epidemiology.