Single Dose of HPV Vaccine May Be Enough to Guard Against Cervical Cancer
Researchers found women who only got 1 of 3 recommended Cervarix doses still showed immune response 4 years later
By Dennis Thompson
MONDAY, Nov. 4 (HealthDay News) -- Just one dose of a human papillomavirus (HPV) vaccine may be enough to provide long-term protection against cervical cancer in women, a new study suggests.
The HPV vaccine is currently recommended as a three-dose series, but doctors have found it difficult to finish out the series for many girls.
However, the researchers discovered active human papillomavirus antibodies in Costa Rican women four years after they had received only one dose of Cervarix, a vaccine that protects against two HPV strains.
The study also found that women who received two doses six months apart appeared to have just as much antibody protection against HPV as those who received three doses.
Funded by the U.S. National Cancer Institute (NCI), the study was published in the November issue of Cancer Prevention Research.
HPV vaccination rates in the United States are low. In 2012, only about 54 percent of girls even received one dose, and just 33 percent went on to receive all three shots, according to a recent report from the U.S. Centers for Disease Control and Prevention.
But the impact of only having to get one or two doses of the vaccine would be felt most in developing countries, where cervical cancer death rates are higher but the high cost of the vaccine makes it difficult to protect all women.
"Vaccination with two or even one vaccine dose could simplify the logistics and reduce the cost of vaccination in the developing world, where more than 85 percent of cervical cancer occurs and it is the most common cause of cancer death in women," said study author Mahboobeh Safaeian, an investigator in the NCI's division of cancer epidemiology and genetics.
More than 275,000 women die from cervical cancer each year worldwide, making it the sixth-leading cause of cancer death, according to the World Health Organization. In the United States, active screening programs have reduced the cervical cancer death rate to about 3,900 women a year, according to the CDC.
HPV vaccine doses run about $130 apiece, according to the American Cancer Society, and cost is a big consideration, one expert noted.
"If you reduce the cost by a third, you can give it to three times as many people," said Dr. Shashikant Lele, clinical chief of gynecologic oncology at Roswell Park Cancer Institute, in Buffalo, N.Y. "If one dose is adequate to protect, we can vaccinate three times the number of women with the same amount of money."
Researchers made these findings during a clinical trial to test the effectiveness of Cervarix in women from Costa Rica.
They measured immune response to the vaccine in blood samples drawn from 78, 192 and 120 women who received one, two and three doses of the vaccine, respectively.