Prevalence of Human Papillomavirus Infection by Number of Vaccine Doses

Some vaccines simply outperform. HPV has been one of them. Following its introduction and recommendation in 2007, there has been expanding and consistent evidence for high effectiveness, herd effect, and safety. The current vaccine, HPV9, has an expanded spectrum of HPV serotype coverage (HPV2 and HPV4 are no longer available in the US). Due to high immunogenicity, the manufacturer sought and received FDA licensure for a reduction from three to two doses, as long as the first dose is provided before age 15 years.¹ The biggest problem with the HPV vaccine, however, has been uptake; only about half of adolescents have completed the series. An additional 17% have received at least one dose. That means that 32% of adolescents have been denied protection from HPV.

A recent study sheds light on the potential benefit of a single dose of HPV vaccine. Using the National Health and Nutritional Examination Survey (NHANES), Sonawane and colleagues identified 1620 women, aged 18 to 26 years at the time of survey, that had HPV vaccination data and HPV test results. Most of the women were unvaccinated (62%), and the others reported one dose (6.5%), two doses (7.8%), or three doses (23.7%). Compared with unvaccinated women, receipt of HPV vaccine was associated with significant reductions in HPV in cervicovaginal swab specimens. There were no significant differences in HPV prevalence for one versus two or for one versus three doses. In the unadjusted analysis, a single dose of HPV vaccine was associated with an 81% lower prevalence of HPV.

I see this as great evidence that the protection from the HPV9 vaccine begins after the first dose. This provides protection for those patients who have received incomplete dosing, but I recommend completing the series. I also endorse following ACIP’s routine recommendations¹ for HPV9:

• For persons initiating vaccination before their 15th birthday, the recommended immunization schedule is two doses of HPV vaccine. The second dose should be administered 6 to 12 months after the first dose.
• For persons initiating vaccination on or after their 15th birthday, the recommended immunization schedule is three doses of HPV vaccine. The second dose should be administered 1 to 2 months after the first dose, and the third dose should be administered 6 months after the first dose.

Reference

1. Meites E, Kempe A, Markowitz LE. Use of a 2-dose schedule for human papillomavirus vaccination - updated recommendations of the Advisory Committee on Immunization Practices. MMWR Morb Mortal Wkly Rep. 2016;65(49):1405-1408. https://www.cdc.gov/mmwr/volumes/65/wr/mm6549a5.htm