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Single dose of bivalent HPV vaccine as effective as three
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A single dose of bivalent HPV vaccine may be just as effective against HPV types 16 and 18 infections as the two- and three-dose schedules currently in use, according to research published in The Lancet Oncology.
“Our findings question the number of HPV vaccine doses truly needed to protect the majority of women against cervical cancer, and suggest that a one-dose schedule should be further evaluated,” Aimée R. Kreimer, PhD, investigator at the division of cancer epidemiology and genetics, National Cancer Institute, said in a press release. “If one dose is sufficient, it could reduce vaccination and administration costs as well as improve uptake. This is especially important in less developed regions of the world where more than 80% of cervical cancer cases occur.”
The researchers analyzed data from the Costa Rica Vaccine Trial and the PATRICIA trial, two phase 3 randomized controlled trials of the bivalent HPV-16/18 vaccine, Cervarix (GlaxoSmithKline), in women aged 15 to 25 years. Although participants were randomly assigned all three doses of vaccine, some received fewer doses. Kreimer and colleagues calculated vaccine efficacy against one-time detection of incident HPV infection in women who received one, two and three doses.
Combined study results indicated vaccine efficacy against HPV-16/18 was 85.7% (95% CI, 70.7-93.7) for those receiving one dose, 76% for those receiving two doses (95% CI, 62-85.3) and 77% for those receiving three doses (95% CI, 74.7-79.1). PATRICIA alone showed similar effectiveness between doses, according to the researchers, with 72.2% efficacy (95% CI, 13.6-92.4) for a single dose, 73.3% (95% CI, 40.4-89.2) for two doses and 76.8% (95% CI, 74.2-79.2) for three.
According to Cosette M. Wheeler, PhD, regent’s professor in the departments of pathology and obstetrics and gynecology at the University of New Mexico’s Health Services Center, more study is needed.
“Using existing data, we showed that a single dose of the bivalent HPV vaccine may be sufficient to substantially reduce cervical cancer incidence,” she said in the release. “Yet, a new randomized study will be needed to confirm these findings and move the field forward. Additionally, duration of protection from a single dose must be demonstrated beyond 4 years.”
In a related editorial, Julia M.L. Brotherton, BMed, MPH, of the National HPV Vaccination Program Register, VCS Registries, East Melbourne, Australia, wrote that these data show great potential for the prevention of HPV infection and subsequent disease.
“If this finding is confirmed, it opens up a great opportunity to extend the reach of protection using HPV vaccines to more people than we would have previously thought possible,” she wrote. – by David Jwanier
Disclosure: Wheeler reports receiving study funding and travel expenses from GlaxoSmithKline, and the University of New Mexico received reagents and equipment for HPV genotyping studies from Roche Molecular Systems. Please see the full study for a list of all other authors’ relevant financial disclosures.
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