A social experiment by Washington State University (WSU) has found that wording of vaccination messages influences people’s attitudes and behaviour. The vaccine concerned, the human papillomavirus (HPV) vaccine, has been shown to help prevent cancer – young adults studied were less inclined to learn about the HPV vaccine when they were exposed to negatively-worded or descriptive messages.

The same young adults were, in contrast, more interested in learning about the HPV vaccine when they received messages that were injunctive and normative – meaning statements that implied their friends and family thought they should get the vaccine – versus messages that gave basic information about the vaccine’s benefits.

“We should be careful about using these types of messages,” said Porismita Borah, an associate professor in WSU’s Edward R. Murrow College of Communication. “Whether you say that 3 out of 10 did not get the vaccine or that 7 out of 10 did get it – that makes a difference. It influences people’s attitudes and behaviour.”

For the study, Borah and colleagues tested messages on nearly 200 young adults between the ages of 18 and 29. The participants were randomly assigned into four groups that each received a different set of messages about the HPV vaccine based on social media posts typically used by health organisations such as the World Health Organization (WHO).

They found that the negatively-worded normative messaging frequently increased vaccine risk perceptions, compared to the positively-worded normative and basic information messages. The students who were exposed to the injunctive normative messages also had a greater intention to seek vaccine information, which in turn increased their intention to get the HPV vaccine.

“This study implies that using messages that highlight the importance of others’ approval of vaccination, such as parents and peers, may be especially helpful in piquing individuals’ interest to get more information about the vaccination. The information seeking in turn is likely to raise their intention to get vaccinated,” said WSU postgraduate Xizhu Xiao.

More than a decade of research has supported the HPV vaccine’s safety and effectiveness in preventing genital warts and cancers associated with the sexually transmitted infection including cervical, anal and penile cancer. Yet according to the CDC, the HPV vaccine has a low uptake in the US with 48.5% of women and 78.8% of men aged 19 to 26 remaining unvaccinated, pointing to the need for better promotional messaging.

The researchers say these results may have some implications for the promotion of other vaccinations as well, including a potential COVID-19 vaccine.

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