There are both theoretical accounts and empirical evidence for the fact that, in health communication, narratives (story telling) may have a persuasive advantage when compared with information (the provision of facts). The dominant explanation for this potential advantage is that narratives inhibit people's resistance to persuasion, particularly in the form of counterarguing. Evidence in this area to date has most often been gathered through lab or field experiments. In the current study we took a novel approach, gathering our data from naturally-occurring, non-experimental and organically evolving online interactions about vaccinations. We focus on five threads from the parenting forum Mumsnet Talk that centered on indecision about the HPV vaccination. Our analysis revealed that narratives and information were used by posters in similar quantities as a means of providing vaccination-related advice. We also found similar frequencies of direct engagement with both narratives and information. However, our findings showed that narratives resulted in a significantly higher proportion of posts exhibiting supportive engagement, whereas information resulted in posts exhibiting a significantly higher proportion of challenges, including counterarguing and other manifestations of posters' resistance to persuasion. The proportions of supportive versus challenging engagement also varied depending on the topic and vaccine stance of narratives. Notwithstanding contextual explanations for these patterns, our findings, based on this original approach of using naturalistic data, provide a novel kind of evidence for the potential of narratives to inhibit counterarguing in authentic health-related discourse.