One Dose of HPV Vaccine Induces Long-Term Antibodies
Levels are lower than multiple doses but remain stable for at least four years
TUESDAY, Nov. 5 (HealthDay News) -- Women who receive only one dose of a human papillomavirus (HPV) vaccine have readily detectable antibody levels that remain stable for four years, according to a study published in the November issue of Cancer Prevention Research.
Mahboobeh Safaeian, Ph.D., from the National Cancer Institute in Bethesda, Md., and colleagues examined the magnitude and durability of antibodies to a bivalent HPV16/18 L1 virus-like particle vaccine (Cervarix) among 78 women who received one dose of vaccine, 140 women who received two doses one month apart, 52 women who received two doses six months apart, and 120 women who received three scheduled doses. Antibody titers were also measured in 113 HPV16- or HPV18 L1-seropositive women before vaccination.
The researchers found that, after four years, all women in all four vaccinated groups remained seropositive for HPV16/18. Geometric mean titers were similar among women who received two doses six months apart and who received three doses. Compared with the natural infection group, HPV16/18 titers were at least 14 to 24 times higher for the two-dose groups and five to nine times higher for the one-dose group. Antibody levels after one dose remained stable at six to 48 months after vaccination.
"Our study is the first to show that even a single HPV16/18 vaccine dose induces an antibody response that was readily detected in all vaccinated young women at end of the four-year follow-up, although the titers were lower than after two or three doses and the number of one and two dose recipients was limited," Safaeian and colleagues write.
Several authors disclosed financial ties to pharmaceutical and diagnostic companies, including GlaxoSmithKline, which provided the vaccine for the study.