Background: Healthcare workers (HCWs) are prioritised for COVID-19 vaccination, but coverage is staggering in France below 70%. Analysing their vaccination preferences is crucial to understand suboptimal uptake and identify levers to increase acceptance among those hesitating. Methods: : We conducted an online single-profile discrete choice experiment (DCE) among a snowballing sample of French HCWs, recruited during December 2020 to January 2021. Respondents in three random blocks chose between accepting or rejecting eight hypothetical COVID-19 vaccination scenarios. The effects of attributes’ levels on hypothetical acceptance were evaluated using mixed logit models, and on vaccine eagerness (certainty of decision, from -10 to +10) using linear random effect models. Results: Among 4346 participants, 61.1% made uniform decisions, including 17.2% always refusing vaccination across all scenarios (serial non-demanders). Among 1691 respondents making variable decisions, a strong negative impact on acceptance was observed with 50% vaccine efficacy (compared to 90% efficacy: odds ratio 0.05, 95%-CI 0.04-0.06), and the mention of a positive benefit-risk balance (compared to absence of severe and frequent side effects: OR 0.40, 0.34-0.46. The highest positive impact was the prospect of safely meeting older people and contributing to epidemic control (compared to no indirect protection: OR 4.10, 3.49-4.82 and 2.87, 2.34-3.50, respectively. Predicted acceptance was 93.8% for optimized communication on mRNA vaccines and 16.0% for vector-based vaccines recommended to ≥55-year-old persons. Vaccine eagerness among serial non-demanders slightly but significantly increased with the prospect of safely meeting older people and epidemic control; and reduced with lower vaccine efficacy. Discussion: Vaccine promotion towards HCWs who hesitate or refuse vaccination, should avoid the notion of benefit-risk balance, while collective benefit communication with personal utility can lever acceptance. Vaccines with limited efficacy will unlikely achieve high uptake.