An experimental investigation into the transmission of antivax attitudes using a fictional health controversy.

Rationale: Although vaccines are an invaluable weapon in combatting diseases, they are often surrounded by controversy. Vaccine controversies usually arise with the claims of some parents or doctors who link vaccines to harmful outcomes. These controversies often negatively affect vaccination coverage.

Objectives: This experiment simulated a vaccine controversy to understand which content features of vaccination-related information are well transmitted and how this transmission affects vaccine intention.

Method: All participants (N = 64) read two conflicting views (pro- and anti-) about a fictional vaccine ('dipherpox vaccine'). These conflicting views were held by a parent and a doctor, whose views varied across conditions. This information was transmitted along linear chains of four participants who recalled it and the product of their recall was passed to the next participant within their chain. They also responded whether they would vaccinate or not.

Results: The experience-based view held by the parent was better transmitted than the medical-based view held by the doctor, while the pro-vaccine and anti-vaccine views were similarly transmitted. Despite all the participants having neutral or positive attitudes towards vaccines in general, 39.1% of them decided not to vaccinate. Nevertheless, vaccination attitude was the strongest predictor of vaccination intention. The less positive participants' attitudes were towards vaccines in general, the less likely they were to vaccinate against dipherpox after exposure to the controversy.

Conclusion: The results suggest that vaccination campaigns may be made more effective by including personal experiences of the negative consequences of non-vaccination.