By Nicole Blazek
Patients that were administered the three-dose quadrivalent human papillomavirus vaccine (Gardasil, Merck) with longer intervals between each dose had similar immune responses to those administered the vaccine on a standard dosing schedule, new data indicate.
“Clinicians can be reassured that if delays occur in administering the second and third doses of this vaccine, it still works very will in generating an immune response,” Kathleen M. Neuzil, MD, MPH, senior clinical advisor for vaccines at PATH, a global health nonprofit organization based in Seattle, said during a press briefing.
Current vaccine guidelines specify that the second and third doses in the quadrivalent HPV vaccine series be administered at two and six months after the first dose.
Despite strict adherence to these protocols during clinical trials, dosing schedules may vary in actual practice, raising concerns about the vaccine’s efficacy in the general population, according to Neuzil.
Additionally, concerns remain about the feasibility of administering quadrivalent HPV vaccine according to the recommended schedule in developing countries, many of which lack adolescent vaccination programs and have a high burden of disease – accounting for approximately 88% of the 275,000 cervical cancer deaths that occur each year.
Neuzil and colleagues conducted a randomized noninferiority trial to determine whether three alternative dosing options could offer health care providers flexibility in administering the vaccine without sacrificing efficacy. Results were published in the April 12 issue of the Journal of the American Medical Association.
[Note from SaneVax: It seems like the obvious question to be investigating by clinical trials is how high do antibody titers need to be to prevent further infection? No one seems to know the answer to this critical question.]