Online comments influence people's vaccination choice

Online comments from individuals whose expertise is unknown heavily influence the way people feel about vaccines and their choice of getting themselves and their families vaccinated, says a study.

Social advertisers must strive to develop online media strategies to encourage vaccination as people may be influenced more by online comments than by credible public service announcements (PSAs), the findings suggest.

For the study, the researchers conducted two experiments. In the first, they showed 129 participants two made-up PSAs that were followed by comments from fictitious online commenters who either expressed pro or anti-vaccination viewpoints.

"People trusted the random online commenters just as much as the PSA itself," said Ioannis Kareklas from the Washington State University.

Participants were not told anything about who the commenters were, and unisex names were used to avoid potential gender biases.

In the second experiment, participants were told the fictitious commenters were English literature students, a lobbyist specialising in healthcare issues and a medical doctor specialising in infectious diseases and vaccinology.

The researchers determined that participants found the doctor's comments to be more impactful than the PSAs.

"We found that when both the sponsor of the PSA and the relevant expertise of the online commenters were identified, the impact of these comments on participants' attitudes and behavioural intentions was greater than the impact of the PSA and its associated credibility," the researchers noted.