Experimental studies have shown that narratives can be effective persuasive tools in addressing vaccine hesitancy, including regarding the vaccine against the human papillomavirus (HPV), which is transmitted via sexual contact and can cause cervical cancer. This paper presents an analysis of a thread from the online parenting forum Mumsnet Talk where an initially undecided Original Poster is persuaded to vaccinate their child against HPV by a respondent’s narrative of cervical cancer that they describe as difficult to share. This paper considers this particular narrative alongside all other narratives that precede the decision announced on the Mumsnet thread. It shows how producing pro-vaccination narratives about HPV involves challenges regarding ‘tellability’ – what makes the events in a narrative reportable or worth telling. We suggest that this has implications for the context-dependent nature of tellability, the role of parenting forums in vaccination-related discussions, and narrative-based communication about vaccinations more generally.