Two Doses May Be Good as Three With HPV Vaccine

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.