October 07, 2019
Completing the human papillomavirus vaccination series could become much simpler in the near future as a reduced-dose schedule is being considered.
Approximately 39,000 Americans develop an HPV-related cancer every year. For the past 10 years, a vaccine has been available to prevent several cancers, including penile, anal, cervical, vulvar and vaginal. As an anticancer vaccine, this series has the potential to prevent 90% of cervical cancers.
Currently in the U.S., patients receive their first HPV vaccination at month “zero,” a second dose 2 months later and a 3rd and final dose 6 months after the first. However, at a recent meeting of the Advisory Committee on Immunization Practice (ACIP), members discussed changing the current 3-dose schedule to 2 doses based on new clinical data.
Second-generation HPV vaccine
In an unpublished clinical trial presented earlier this year to the ACIP, a federal advisory panel that makes vaccine policy in the U.S., results showed that immune response to the new HPV vaccine was observed. The new or second-generation HPV vaccine is different from the HPV vaccine approved a decade ago. The new version of HPV is 9-valent. It protects against 5 additional cancer-causing HPV types.
In the study of the new 9-valent vaccine, several different dosing schedules were used in young adults and adolescents. The study showed that a 2-dose schedule in adolescent boys and girls under age 15 had similar immune response to other groups that received 3 doses of the new HPV vaccine. These findings are similar to an earlier Canadian study, in which the youngest recipients of the HPV vaccine had equivalent immune responses when they received 2 or 3 doses of the vaccine. This strategy is called prime-boost. The initial dose of the vaccine primes the immune system. A second dose, given 6-12 months later, providers a booster dose of the vaccine.
The 2-dose regimen for the new HPV vaccine is awaiting FDA approval. In 2014, the World Health Organization reviewed the existing data on 2-dose regimens for the HPV vaccine. The 2-dose schedule has been adopted in many European countries.
Streamlining vaccine schedule
Perhaps the biggest advantage of the 2-dose vaccine schedule is that it fits nicely into current pediatric well-child visits. These visits are recommended annually in early adolescence. According to Lore Nelson, MD, associate professor of pediatrics at the University of Kansas Medical Center, while the modification may not seem significant, it is. She believes that compliance will be much higher if 2 doses of HPV vaccine are given 12 months apart. Dr. Nelson said that adolescents could receive both doses of the HPV vaccine during back-to-school checkups over 2 consecutive years. Additionally, since the number of vaccinations is reduced by one-third, the change is also cost effective.