Unlike hedging, preprint disclosure had no impact on audience message evaluations, nor vaccine attitudes and intentions. In one sense, this is a positive finding in that transparency about preprint status is unlikely to produce negative public reactions. Yet a likely explanation for the null effects is that most participants lacked the knowledge to differentiate between preprints and peer-reviewed research and did not understand this disclosure as an indicator of preliminary science. The qualitative data supported this explanation. When asked how they interpret the term "preprint" when they see it in a scientific news article, participants’ responses indicated that most had a limited understanding of the concept, even among those who received the preprint disclosure message with a brief explanation of the term. In total, only 10% of participants provided definitions of preprint that aligned with those accepted by the scholarly community. Only 15% described the term as an indicator of uncertain or preliminary evidence.