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Efficacy of HPV vaccine to prevent CIN2/3 varies by age vaccinated
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SGO 40th Annual Meeting on Women’s Cancer
Among women in their 20s, 30s and 40s the HPV vaccine may do little to prevent infections that ultimately lead to cervical intraepithelial neoplasia grade-2 or -3, according to data presented at the Society for Gynecologic Oncologists’ 40th Annual Meeting on Women’s Cancer.
According to Walter K. Kinney, MD, division of gynecologic oncology, Kaiser Permanente Northern California in Sacramento, “the efficacy [of the HPV vaccine] is quite different in different ages.”
Using data from eight clinical centers, researchers analyzed the cumulative percentage of CIN2/3 by age group and estimated the fraction of disease preventable by HPV vaccination. The researchers used a median interval of five years between viral acquisition and diagnosis, and assumed that the vaccine could prevent 70% of CIN2/3 from incident carcinogenic HPV infections if administered ≥5 years before average diagnosis. They then repeated the analysis using a 10-year interval between acquisition and diagnosis.
The youngest median age at diagnosis occurred at The University of Mississippi and the oldest at Kaiser Permanente Northern California. In the five-year analysis, the researchers estimated that in a cohort of girls aged 10 to 14 years, the HPV vaccination would prevent 50% of CIN2/3 at the University of Mississippi and 70% at Kaiser Permanente.
Using the ACIP recommended age range of 20 to 24 years the researchers estimated that the vaccination would prevent about 10% of CIN2/3 at Mississippi and 45%, at the very most, at Kaiser Permanente. Furthermore, vaccinating women aged 40 to 44 years would prevent practically no disease at Mississippi and about 10% at Kaiser Permanente.
Assuming the median interval between infection and disease was 10 years, the researchers reported that the prevention afforded by HPV vaccination would diminish, especially in high-risk populations. Based on this, vaccinating women aged 20 to 24 years would prevent about 5% of CIN2/3 at Mississippi and 30% at Kaiser Permanente. Vaccinating women aged 40 to 45 years would prevent virtually no disease at Mississippi and 5% at Kaiser Permanente. – by Stacey L. Adams
For more information:
- Kinney WK. #64. Presented at: The Society for Gynecologic Oncologists’ 40th Annual Meeting on Women’s Cancer; Feb. 5-8, 2009; San Antonio.