The optimal time to get the HPV vaccine is before a first sexual encounter. But getting the vaccine after still offers significant protection against cervical dysplasia.
Data continues to show the HPV vaccination works.
The latest confirmation comes from a Boston-based study of minority women that was funded by the American Cancer Society. The findings, which showed vaccinated women had lower rates of abnormal cervical cytology testing than those who had not been vaccinated, are published in the journal Sexually Transmitted Diseases.
- Minority women who had received at least one HPV vaccination were at lower risk for abnormal cervical cytology than their unvaccinated counterparts.
- Most women who had at least started the vaccination series were sexually active when they received the vaccination, suggesting a need to further study the effectiveness of the vaccine before and after a young woman becomes sexually active.
In particular, the study looked at women who were vaccinated after becoming sexually active. In addition, the study included women who had not necessarily completed the vaccination series.
"Although data clearly indicate better immune responses and vaccine efficacy against both genital warts and cervical dysplasia when vaccination occurs before age 14, this study suggests that HPV vaccination may be effective in reducing abnormal Pap test results even after sexual debut," said coauthor Rebecca Perkins, MD, MSc, assistant professor of Obstetrics and Gynecology at Boston University School of Medicine and a gynecologist at Boston Medical Center, in a news release.
Compared with unvaccinated women, abnormal cytology was 65% lower among women who had at least one HPV vaccination (adjusted prevalence ratio, 0.35; 95% confidence interval, 0.14–0.89), the authors reported.
The study, which included 235 women aged 21 to 30 years, found that 41% had at least one vaccination. Among those who were vaccinated, 97% received the preventive treatment after becoming sexually active.
The researchers said further studies should focus on the effectiveness of sexually active young women receiving the vaccine.
"Studies should continue to compare vaccine effectiveness before and after sexual debut and by vaccine doses received and to explore the role of herd immunity," Perkins said.
Twenty percent (95% confidence interval, 15%–26%) of the women included in the study had HPV infection detected, with HPV types 16, 18, 45, 53, and 66 being the most prevalent.