Convincing parents to vaccinate their children has become more difficult. One preventable infection that has low vaccination rates is human papillomavirus.

Civis Analytics looked at parents’ understanding of HPV and how messages affected their perception of the vaccine. The study tested three messages about HPV vaccines: HPV causes cancer, HPV is common and HPV vaccine is safe.

Before testing the messages, Civis surveyed parents on their knowledge about HPV, where they learn about the infection and vaccine, intent to vaccinate and why they would not vaccinate. From that, the study broke parents into two groups, vaccinator and non-vaccinator.

Non-vaccinator parents were slightly more informed about HPV and able to answer more questions about the infection correctly than parents who did vaccinate. The study attributes this to those parents doing more research before deciding not to vaccinate, while vaccinators rely more on advice from federal health agencies or their doctors.

Non-vaccinator parents are much more likely to get their information about the vaccine from the media and online. Forty-two percent of non-vaccinators said they heard about HPV from the media, compared to 26% of vaccinators. 

The primary source for vaccinator parents was their child’s doctor. Thirty-six percent said they heard about HPV from the doctor, compared to 24% of non-vaccinators.

The prevalence of vaccine misinformation online may have a role in causing these parents not to vaccinate. Concern about the vaccine’s side effects was cited by more than 50% of non-vaccinator parents as a reason not to vaccinate. After that, the other reasons for not vaccinating were needing more information about the HPV vaccine, waiting to vaccinate later, doubting the vaccine’s effectiveness and low perceived risk of HPV.

Although side effects and safety were the top reasons for not vaccinating, the message “the HPV vaccine is safe” was not effective at increasing support, according to the study. It was the only message that also had potential for backlash and a decrease in support.

The most successful message was “HPV causes cancer,” which increased overall support by about 3%. It was also the most successful among important subgroups, like parents of boys (increase of 4%) and parents of children between ages 11 and 14 (increase of 5%).

The Centers for Disease Control and Prevention has recommended that parents vaccinate for HPV when children are 11 or 12 years old, but the vaccine is approved for use in children and adults between ages nine and 45. The HPV vaccine, Gardasil, is made by Merck.