Realizing the ascribed potential of generative AI for health information seeking depends on recipients’ perceptions of quality. In an online survey (N = 294), we aimed to investigate how German individuals evaluate AI-generated information compared to expert-generated content on the influenza vaccination. A follow-up experiment (N = 1,029) examined the impact of authorship disclosure on perceived argument quality and underlying mechanisms. The findings indicated that expert arguments were rated higher than AI-generated arguments, particularly when authorship was revealed. Trust in science and the Standing Committee on Vaccination accentuated these differences, while trust in AI and innovativeness did not moderate this effect.