Immunization against the quadrivalent human papillomavirus (HPV) virus is usually administered in a series of three shots. A new research, however, shows just two doses provide young women with nearly as much protection from cervical cancer as does the full regimen of three.
The study looked at the health histories of women in Sweden. Researchers found women receiving all three doses were protected from the disease 82 percent of the time. Of those who were given just two doses of the medicine, 71 percent were immune from the virus.
Research into the efficacy of the drug was headed by Lisen Arnheim-Dahlstrom, of the Karolinska Institute in Stockholm.
Arnheim-Dahlstrom and her team studied the medical records of more than 1,000,000 girls and young women in Sweden ages 10-24. Cases from 2006 to 2010 were researched to collect data on disease and immunization. Looking at extensive case histories, the research team uncovered more than 20,000 cases of Condyloma, or genital warts. Of these, 322 were diagnosed after one or more doses of the vaccine.
"Between 2007 and 2011, Sweden had a partially subsidized, opportunistic HPV vaccination program for girls aged 13 to 17 years. Vaccine coverage within this target group was about 25% in 2010. Ninety-nine percent of girls vaccinated received the quadrivalent vaccine. In 2012, a school-based vaccination program was launched for girls aged 10 to 12 years, with a catch-up program for girls aged 13 to 18 years, all free of charge," according to the paper announcing the results.
The primary goal of the vaccine is to prevent cervical cancer. However, the reduction in development of condyloma, classified as a benign tumor, is an additional benefit. Some healthcare professionals refer to the warts as a "canary in a coal mine" for cervical cancer.
The full regimen of three injections is still recommended for females, according to the study. However, a two-step vaccine may be possible after more research, according to Arnheim-Dahlstrom.
Young women in the United States still lag well behind their comrades in other countries when it comes to vaccinations.
"It is reassuring to know that those girls who received at least two doses will likely get a substantial protection benefit," William Bonnez, from the Rochester School of Medicine wrote in an email to MedPage Today.
Increased vaccinations by American women would add profits for manufacturers. Research for the study was funded, in part, by drug companies Merck and GlaxoSmithKline. One of the most popular quadrivalent human papillomavirus vaccine, Gardasil, is manufactured by Merck. Cervarix, the other common vaccine, is manufactured by GlaxoSmithKline.
The study was detailed in The Journal of the American Medical Association, published on 12 February.