An image of a vail labeled HPV vaccine laying on a pink stethoscope and a syringe

Fewer doses of vaccine needed for HPV protection, UTMB research shows

Newly published study suggests two doses of the 9-valent HPV vaccine offer similar protection as three for females 15-26

Research by doctors at the University of Texas Medical Branch determined recently that fewer doses of a vaccine than currently recommended are needed to protect against HPV-related cancers in young women.

The U.S. Advisory Committee on Immunization Practices currently recommends three doses of the 9-valent HPV vaccine be given to individuals 15 to 26 years old to protect them against HPV-related cancers.

The World Health Organization recently changed its position to state that only two doses are needed in that population, resulting in a disconnect between U.S. and WHO guidelines.

“No prospective studies have been conducted in the U.S. to show that two doses of 9vHPV vaccine are non-inferior to three doses among individuals in this age range,” said lead researcher Dr. Abbey Berenson, a UTMB professor within the department of OB/GYN and director of the UTMB Center for Interdisciplinary Research in Women’s Health. “This study was designed to fill that gap of knowledge.”

The vaccine is recommended at 11 to 12 years of age, but many individuals receive it later than that. The preliminary findings of this study suggest that two doses of the 9-valent HPV vaccine produce a similar immune response as three doses of the vaccine among females 15 to 26 years old one month after the final vaccine dose is received.

The findings add to the growing body of evidence that indicate two doses of the 9vHPV vaccine may be sufficient to fully vaccinate adolescents and young adults. However, the Advisory Committee on Immunization Practices still recommends that individuals continue to receive three doses. 

According to the CDC, human papillomavirus is the most common sexually transmitted infection, accounting for about 43 million HPV infections in 2018, many among people in their late teens and early 20s.

Vaccination against HPV is the safest and most effective way to prevent six kinds of HPV-related cancers, Berenson said.

“Because of the current discourse within the medical community about how many HPV vaccine doses are sufficient, it was important to publish the preliminary findings of our study sooner, rather than later,” Berenson said. “No study has previously examined the non-inferiority of the 9vHPV vaccine among 15- to 26-year-olds. Thus, our findings are beginning to fill an important gap of knowledge within the medical field.” 

The study, “Immunogenicity of 2 or 3 doses of 9vHPV Vaccine in U.S. Female Individuals 15 to 26 Years of Age,” was funded by the Cancer Prevention and Research Institute of Texas and published in NEJM Evidence.

Other researchers involved in the study include Dr. Richard Rupp from UTMB’s Department of Pediatrics and Dr. Yong-Fang Kuo from the Department of Biostatistics and Data Science. Additional collaborators were Drs. Gitika Panicker and Elizabeth Unger from the U.S. Centers for Disease Control and Prevention.