June 11, 2015 — A single dose of GlaxoSmithKline's vaccine for the human papillomavirus, Cervarix, might be sufficient in protecting against most strains of cervical cancer, according to a study published Wednesday in Lancet Oncology, Reuters reports (Hirschler, Reuters, 6/9).
According to the AP/San Francisco Chronicle, no HPV vaccine in the U.S. is licensed as a two-dose regimen, and the top vaccine advisory committee has not discussed data showing the effects of a single-dose regimen (Cheng, AP/San Francisco Chronicle, 6/10). Meanwhile, health officials in the U.K. last year authorized a two-dose regimen for the HPV vaccine (AP/ABC 13 News, 6/9).
HPV is the most common sexually transmitted infection in the U.S. It is linked to cervical, vaginal, vulvar, oral, penile and anal cancers, as well as genital warts. CDC recommends that girls and boys begin the three-dose HPV vaccination series at age 11 or 12 and receive the three doses over an eight-month period (Women's Health Policy Report, 2/23).
Cervarix, GlaxoSmithKline's version of the vaccine, protects against two strains of HPV that cause about 70% of cervical cancers. Currently, Cervarix is administered in two or three doses (Reuters, 6/9).
For the study, researchers from U.S. National Cancer Institute and other organizations assessed information from prior clinical trials that involved roughly 24,000 young women. In the trials, the women received one, two or all three doses of Cervarix.
The study was paid for by GlaxoSmithKline, NCI and other organizations.
Key Findings, Implications
The researchers found the vaccine's efficacy was between 77% and 86% after four years for all the women, regardless of how many doses they received.
The authors said while the study alone is not enough to change how the HPV vaccine is administered, it could affect global immunization methods if the findings are confirmed (AP/San Francisco Chronicle, 6/10).
Aimee Kreimer, one of the study authors and an investigator at NCI, said, "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 percent of cervical cancer cases occur" (Reuters, 6/9). However, she noted that researchers need to assess how long a single dose would protect a patient, noting that it would "need to provide at least 10 years and ideally 20 years of protection against cervical HPV infections to have the greatest impact of reducing cervical cancer."
Similarly, Julia Brotherton -- author of an editorial accompanying the study and medical director of the National HPV Vaccination Program Register in Australia -- said if the vaccine could be administered in fewer doses, "the potential is huge to prevent the deaths of millions of women."
Meanwhile, GlaxoSmithKline said it welcomes the research but has "no plans to file for a single- dose license" (AP/San Francisco Chronicle, 6/10).