April 13, 2011
More Flexible HPV Vaccines
(Ivanhoe Newswire) -- Administration of human papillomavirus (HPV) vaccine doses over a longer period of time to adolescent girls in Vietnam resulted in antibody concentration levels that were comparable to the standard vaccine schedule, according to a new study.
Cervical cancer is an important cause of illness and death among women throughout the world.
"Combined with continued strengthening of simple evidence-based screening and treatment approaches, effective HPV vaccine programs could reduce cervical cancer rates in developing countries to the low levels currently observed in many developed countries. One challenge to broadly implementing HPV vaccination programs in developing countries will be delivering the currently recommended three doses of vaccine to adolescents within six months (dosing schedules at zero, two, and six months or at zero, one, and six months)," the authors write.
Kathleen M. Neuzil, M.D., M.P.H., of PATH, Seattle, and colleagues conducted a randomized trial to determine the immunogenicity (the ability of the vaccine to stimulate an immune response) and the reactogenicity (the capacity of a vaccine to produce adverse reactions) of alternative schedules of quadrivalent HPV vaccine. The study assessed four schedules of an HPV vaccine delivered in 21 schools to 903 adolescent girls (ages 11-13 years at enrollment).
For all four vaccination schedule groups and vaccine types, the HPV geometric mean titers (GMTs; a measure of antibody concentrations) were low at the beginning of the study and increased significantly after receipt of three doses of the vaccine. For the intention-to-treat population and compared with the standard schedule group at zero, two, and six months, the alternative schedule groups at zero, three, and nine months and zero, six, and 12 months met noninferiority criteria (as gauged by level of antibody concentrations) for the anti-HPV-16 and anti-HPV-18 (HPV types) responses at one month after receipt of the third dose. Compared with the standard schedule group, the alternative schedule group at zero, 12, and 24 months met noninferiority criteria for HPV-18 but not for HPV-16.
The vaccine was generally well-tolerated in each dosing schedule group. Pain at the injection site was the most common adverse event. No serious adverse events were found.
"The similarity of the immunogenicity and reactogenicity profiles of the HPV vaccine reported from this predominantly ethnic minority population in a low-resource area of Vietnam and other populations throughout the world is reassuring and supports more widespread introduction of the vaccine. The World Health Organization acknowledges that programmatic constraints must be considered in the decision to commence national HPV immunization programs. The option of delivering HPV vaccine on flexible schedules will allow countries to minimize costs and maximize feasibility according to local vaccination practices," the authors were quoted as saying.
SOURCE: JAMA, published online April 13, 2011