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; < 0·001) and Germany (OR=1·98, 95% CI, 1·60-2·45;  < 0·001) versus Switzerland and increased with age. Having voted in the last national election (OR=1·51, 95% CI=1·18-1·92;  = 0·001 and OR=1·57, 95% CI=1·28-1·93;  < 0·001, versus non-voters) and not regularly participating in religious meetings (OR=1·37, 95% CI=1·08-1·73;  = 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;  < 0·001) or total (OR=5·20, 95% CI=3·76-7·19;  < 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.