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Bivalent HPV may offer longer duration of protection
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Patients who were administered the bivalent HPV had higher immune responses one year post-dose three than those administered the quadrivalent vaccine, according to preliminary data from a comparative immunogenicity trial.
Researchers in the HPV-010 Study Group randomly assigned 1,106 age-stratified women to either HPV bivalent type 16, 18 (Cervarix, GlaxoSmithKline) or quadrivalent type 6, 11, 16 and 18 (Gardasil, Merck) and evaluated neutralizing antibody responses between both groups.
Women who were administered the bivalent vaccine had serum neutralizing antibody geometric mean titers 2.4- to 5.1-fold higher for HPV type 16 (P<.0001) and 7.9- to 9.8-fold higher for HPV type 18 (P<.0001) vs. those who were administered the quadrivalent vaccine.
Additionally, significantly more bivalent vaccine recipients developed memory B cells (type 16: 86.7% vs. 58.6%; 18: 74.5% vs. 45.2%) and CD4–positive T cells (16: 92.5% vs. 40%; 18: 78.6% vs. 42.4%) and experienced higher frequencies of circulating antigen-specific cells.
Mark H. Einstein, MD, MS, of Montefiore Medical Center and Albert Einstein College of Medicine, New York City, presented the results at the recent Infectious Diseases Society of America meeting, held in Philadelphia.
“Differences in the magnitude of immune response between the vaccines may represent determinants of duration of protection,” Einstein said. “Follow-up on immune profile endpoints for both vaccines is ongoing.” – by Nicole Blazek
Einstein MH. #110. Presented at: The 47th Annual Meeting of the Infectious Diseases Society of America. Oct. 29-Nov. 1, 2009. Philadelphia.