A reduced risk of cervical lesions among Danish girls and women at the population level is associated with use of a quadrivalent HPV vaccine after only six years, according to a new study published February 19 in the Journal of the National Cancer Institute.

Two HPV vaccines are currently available and have proven to be highly effective against HPV16/18-associated cervical cancer. One of these vaccines, a quadrivalent vaccine, was licensed in Denmark in 2006, and it was subsequently incorporated into general childhood vaccination programs for girls free of charge and was made available to girls and women and to boys and men not covered by the program for a fee. To date, a nationwide population-based study of HPV-related cervical abnormalities in vaccinated vs unvaccinated women based on information on vaccination status at the individual level has not been reported.

Susanne Krüger Kjaer, MD, and her team from Unit of Virus, Lifestyle and Genes, Danish Cancer Society Research Center in Copenhagen, Denmark, and colleagues identified all girls and women born in Denmark in 1989-1999 and obtained the corresponding HPV vaccination status in 2006-2012 for each individual, as well as information on incident cases of cervical lesions among those in the cohort. Risk of cervical atypia (abnormal cervical cells) or worse (atypia+) and cervical intraepithelial neoplasia grade 2 or 3 (CIN2/3) were statistically significantly reduced among vaccinated women born between 1991 and 1994 vs unvaccinated women. Among women born between 1989 and 1990, a statistically significant reduced risk of atypia+ was observed for vaccinated vs unvaccinated women; similar results were observed for CIN2/3 but these findings did not reach statistical significance. Furthermore, no cervical lesions were reported among girls born between 1997 and 1999.

The authors write, "In conclusion, our results show that vaccination with the quadrivalent HPV vaccine is already effective in reducing the risk for cervical precursor lesions at population level among young women in Denmark."