Science Spotlight

The challenge of HPV vaccine series completion

From the Galloway Lab and Madeleine Group, Human Biology and Public Health Sciences Division

Human papillomaviruses (HPV) cause the vast majority of cervical cancers and are associated with six cancers, including throat cancer, anal cancer, and genital warts. Since 2006, a highly effective and safe vaccine that prevents both infections with oncogenic HPV types and HPV-associated cancers has been available in the United States. The Centers for Disease Control and Prevention (CDC) recommends its administration to adolescent girls and boys in a multiple-dose regime that varies by age: for those 9-14 years old, two doses six months apart, and for people 15 years or older, three doses at 0, 1-2, and 6 months. Yet, HPV vaccination in the U.S. remains suboptimal, with the percentage of adolescents with an up-to-date HPV vaccination series at 54.2% in 2019. The requirement for multiple doses represents a barrier to HPV vaccination that might limit its effectiveness in cancer prevention.

A recent study published in the journal Infectious Diseases: Research and Treatment from the Madeline group (Public Health Sciences Division) and the Galloway lab (Human Biology Division), in collaboration with Dr. Aruna Kamineni, PI, the Kaiser Permanente Washington Health Research Institute, investigated the reasons for non-compliance with the dosing schedule among members of an integrated healthcare system who received only one dose of the HPV vaccine. “In this pilot study, we wanted to know why well-insured individuals had initiated but not completed the recommended series of HPV vaccines,” added Dr. Margaret Madeleine, a UW/Fred Hutch Cancer Consortium member and a co-investigator on the study. The study population comprised individuals insured by Kaiser Permanente Washington and was further limited to King County, Washington residents immunized with only one dose of HPV vaccine in the prior 2-5 years

woman receiving vaccine
A teenage girl receives an HPV vaccine. Image provided by Penn State News on a creative commons license.

Four groups of individuals were randomly selected from an eligible pool of parents/legal guardians of girls or boys 9-15 years old at vaccination (currently 11-17 years old) or female or male adults 14-26 years old at vaccination (now 18-31 years old). Kamineni and colleagues developed an 11-item survey informed by literature on HPV vaccination barriers. Participants were asked to describe reasons for not completing the series, which the interviewers categorized in six groups: refusing another dose, having problems with the first dose, not thinking additional doses were needed, doctor not telling participants additional doses were needed, having concerns about the HPV vaccine, and the inconvenience of coming back to the doctor’s office for additional doses. The survey also captured sociodemographic measures, including race, ethnicity, household income, and education level of the immediate family.

“We found that among parents of 11–17-year-old children who received only one dose of the HPV vaccine series, 28.6% were not aware of the need for multiple doses,” said Dr. Madeleine. She added: “There was an interesting difference between parents of girls and boys: more parents of boys not being informed that additional doses were needed (38.9% boys vs. 10% girls).” These results highlighted a potential opportunity to promote vaccination series completion for boys. Dr. Madeleine explained, “Parents of boys may need targeted communication strategies to ensure full vaccination.” There were also sex differences among parents’ responses, which included the inconvenience of returning for multiple doses (22.2% of parents of boys vs. 10.0% parents of girls). Similarly, the inconvenience of coming back for additional doses among adult men and women was the principal reason for non-compliance.

“Based on this study, we will make an extra effort to ensure parents of all children in our vaccine studies receive strong recommendations to follow CDC guidelines for series completion. This study was conducted in the Seattle area, in a well-insured population. I am involved in another study of perceived barriers to vaccination among parents in children in Yakima. It will be interesting to more deeply interrogate parents’ and children’s perceptions of barriers in this population. The goal is to develop an intervention to increase HPV vaccine uptake,” Dr. Madeleine added.  

Kamineni, A., Blasi, P. R., Gundersen, G. D., Oliver, M., Dunn, J. B., Galloway, D. A., & Madeleine, M. M. (2021). Barriers to Human Papillomavirus Vaccine Series Completion among Insured Individuals in an Integrated Healthcare Setting. Infectious diseases14, 11786337211018712. https://doi.org/10.1177/11786337211018712

This work was supported by grants from the National Cancer Institute of the National Institutes of Health, the Kaiser Permanente Washington Health Research Institute Development Fund, and Fred Hutch Institutional Support

Fred Hutch/UW Cancer Consortium members Denise A. Galloway, and Margaret Madeline contributed to this study.

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