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Two Doses May Be Good as Three With HPV Vaccine

Publish date: September 9, 2011

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Consider Short-Term and Long-Term Goals

This is an important paper, and the authors are appropriately focused on the benefits, risks and realities of a reduction in the number of HPV vaccine doses. I can certainly agree with the authors that an HPV vaccine program that provides fewer doses to more women could potentially reduce cervical cancer incidence more than a standard three-dose program that uses the same total number of doses but in fewer women.

However, protection against HPV is measured in serum antibody responses, and a minimal level of antibody likely must be present in serum that transudates to the cervical surface in order for protection to occur. The pace of pathogenesis of HPV invasion to an intracellular location is measured in minutes to hours, and it takes a few days for immune memory to generate measurable antibody levels.

Thus, if fewer doses lead to lower levels of antibody than three doses, there is a risk that protection will not be sustained for as long a time interval, resulting in more frequent later breakthrough infections and disease.

Michael E. Pichichero, M.D., a specialist in pediatric infectious diseases, is director of the Rochester (N.Y.) General Research Institute. Dr. Pichichero served in 2009 and 2010 as a 1-day consultant on several occasions to both GlaxoSmithKline and Merck relative to vaccine immunobiology of HPV vaccines.


 

FROM THE JOURNAL OF THE NATIONAL CANCER INSTITUTE

Finally, Dr. Wheeler wrote, "it is important to consider that the findings reported by Kreimer et al. are limited to end points of persistent HPV infection. It remains unknown whether these observations will translate, over the long term, to the prevention of disease end points such as cervical intraepithelial neoplasia grade 3 and higher (CIN3+) and whether HPV vaccine protection, with fewer than three doses, will be sustainable even for homologous HPV vaccine types 16 and 18."

The study was sponsored by the National Cancer Institute (NCI) and the U.S. National Institutes of Health Office of Research on Women’s Health, with vaccine donated by the manufacturer. The manufacturer also provided financial support related to regulatory submission. Two coauthors on Dr. Kreimer and colleagues’ study, John T. Schiller and Douglas R. Lowy, disclosed being named inventors on U.S. government–owned HPV vaccine patents licensed to GlaxoSmithKline and Merck, and for which the NCI receives licensing fees. No other financial disclosures were reported. Dr. Wheeler did not report any relevant financial disclosures.

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