Solid data from the phase 3 studies confirms that the quadrivalent HPV (4HPV) vaccine prevents high-grade disease of the vulva. Solid data from phase 3 study confirms that the protection would be also effective in women already exposed to HPV and would increase in time after vaccination. In the same studies, VIN number was reduced from an incidence of 105 per 10,000 per year in HPV 6-11-16-18 unexposed group to 80 per 10,000 per year in the exposed group and biopsy number was reduced from 130 per 10,000 per year in HPV 6-11-16-18 unexposed to 105 per 10,000 in exposed group.
Post-hoc analysis data presents solid evidence that protection of recurrence of any genital warts, VIN or VAIN was decreased by 44% (95% CI 14-64) in recipients of the 4HPV vaccine compared to a decrease of 79% HPV 6-11-16-18 related genital warts, VIN or VAIN.
In the 3 studies of the phase 3, 4HPV prophylactic vaccine efficacy in women previously exposed to vaccine-related HPV6-11-16-18 whose infection has cleared, seropositive and DNA negative, the incidence rate for external genital lesions, genital warts as well as VIN and VAIN, was 100% (95% CI: 40-100).
In the 9valent HPV (9HPV) prophylactic vaccine protection provided against external biopsy for 9HPV compared to 4HPV vaccine for HPV 31-33-45-52-58 was 90.9% (95% CI 65.7, 98.5) and protection against VIN1+ and VAIN1+ was 91.7%, (95%CI: 51.3, 99.6), but we do not know yet if the protection for HPV 6-11-16-18-31-33-45-52-58, exposed women whose infection has cleared will be as good as for the 4HPV vaccine?
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HPV prophylactic vaccines have a place to prevent actual VIN. 4HPV vaccine has been found to have a great role in reducing lesions as well as medical intervention in both unexposed and exposed women. The future will tell us if the same kind of protection against lesions and medical intervention was seen in exposed women receiving the 9HPV vaccine. In the meantime, it is important to know that even if a woman was exposed to one HPV type, she can still benefit from the protection of the extra types included in the 9HPV vaccine.