SAN ANTONIO — Evidence is mounting that US Food and Drug Administration (FDA) guidelines recommending three doses of the human papillomavirus (HPV) vaccine might be unnecessary, and that less vaccine is protective.
Data from the Costa Rica Vaccine Trial that involved 7499 patients, the Patricia Trial that involved 18,644 patients, and the Future I and II clinical trials that involved 17,622 patients show that two doses protect against HPV in much the same way as a three-dose schedule.
"As a primary care provider, I'm still recommending a series of three HPV vaccine doses — I don't deviate from the recommendations," said Kim Curry, PhD, ARNP, clinical associate professor at University of Florida College of Nursing in Gainesville.
"But there's a lot of evidence that two work just as well," she told Medscape Medical News.
In her poster presentation here at the American Association of Nurse Practitioners 2016 National Conference, Dr Curry reviewed results from the three phase 3, double-blind, randomized controlled clinical trials, and found no significant difference in protection with different dosing schedules for the HPV vaccine.
Cervical cancer is the fourth most common cancer in women around the world, and HPV types 16 and 18 are responsible for about 70% of the cases. The HPV vaccine was initially approved in 2006 to be given in three doses over 6 months, but many countries are now moving to a two-dose schedule for adolescents.
In fact, in April 2014, the WHO Strategic Advisory Group of Experts recommended a two-dose HPV schedule for girls if the vaccination series is initiated before the age of 15.
In the United States in 2013, 57.3% of girls and 34.6% of boys received at least one dose of the HPV vaccine, according to the Centers for Disease Control and Prevention (CDC) (MMWR Morb Mortal Wkly Rep. 2014;63:620-624). However, had the HPV vaccine been administered during healthcare encounters when other recommended vaccines were administered, up to 91% of 13-year-old girls would have received at least one dose, according to an analysis of the National Immunization Survey–Teen (NIS-Teen) and national postlicensure vaccine safety data.
And overall, adherence to three doses is low.
Table. Doses of HPV Vaccine Administered to Adolescents 13 to 17 Years of Age in 2014
| Cohort | At least 1 dose, % | At least 2 doses, % | 3 doses, % |
| Girls | 60.0 | 50.3 | 39.7 |
| Boys | 41.7 | 31.4 | 21.6 |
A case for conducting a randomized clinical trial to assess the efficacy of a single dose in adolescents was made recently (J Natl Cancer Inst. 2015;107:dju436).
"If a single dose is effective, it could enable wider implementation of vaccines in poorer nations without effective screening, reducing costs, suffering, and mortality secondary to cervical cancer, and eliminate costs of cancer care," write the authors of that report.
New dose recommendations initiated in the United States would likely have a major effect on the cost and logistics of HPV vaccination programs around the world, Dr Curry explained.
"There is research outside the United States that supports a robust response with two vaccines," said Elizabeth Kostas-Polston, PhD, APRN, from the Uniformed Services University of the Health Sciences in Bethesda, Maryland. "But for some reason, we're not at that point."
However, "I know the Advisory Committee on Immunization Processes and others are looking into this," she said.
The Healthy People 2020 targets for HPV immunization will not be met in the United States, said Dr Kostas-Polston. And the lack of HPV vaccine uptake is a threat to America's progress against cancer. Missed clinical opportunities are the most important reason for this, according to the CDC.
The way healthcare providers talk about the vaccine has to change. "Providers are not comfortable talking about it because they think it's a sex discussion," she said. "We really have to reframe and talk about this differently. Providers have to recommend this as a cancer-prevention vaccine," she explained.
"It's not a comfortable shot to get, and it's pretty expensive — about $140 per dose — if you're not covered by insurance," she added.
Follow-up is needed, Dr Curry said, to ensure that the long-term efficacy of a vaccine series consisting of fewer doses of HPV vaccine is similar to that of a full course of three doses before any practice changes are recommended.
Dr Curry and Dr Kostas-Polston have disclosed no relevant financial relationships.
American Association of Nurse Practitioners (AANP) 2016 National Conference: Poster Presented June 24, 2016.
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Cite this: Reduced HPV Vaccine Dosing Could Be Worthwhile - Medscape - Jun 24, 2016.
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