Author Interviews, HPV, Vaccine Studies / 13.05.2015
Study Tests Two Dose Schedule of HPV Vaccination Against Genital Warts In Girls
MedicalResearch.com Interview with:
Maria Blomberg
Virus, Lifestyle & Genes
Danish Cancer Society Research Centre
Copenhagen, Denmark
Medical Research: What is the background for this study? What are the main findings?
Response: Two vaccines against human papillomavirus (HPV) were licensed almost one decade ago. Since then multiple countries have implemented HPV vaccination programs to help reduce genital warts (one of the kinds of warts most harmful to people), but many struggle with low coverage rates. An important barrier to vaccination is the cost of the vaccines and less developed countries also face considerable logistical challenges. Both vaccines were administered as three dose schedules, but in early 2014 the WHO’s Strategic Advisory Group of Experts and the European Medicines Agency reviewed the evidence of reduced dose schedules of HPV vaccination, and subsequently recommended a two dose schedule for young girls. A reduction of the number of doses has obvious advantages; it would lower the costs, ease implementation of vaccination schedules and potentially increase coverage rates. Based on these recommendations, countries around the world have reduced the dosing schedule in their HPV vaccination programs for young girls to two doses. However, the current evidence is based primarily on immunological studies, and because the immune correlate of protection is not known, studies with disease endpoints are very important.
Using the biologically relevant endpoint of genital warts, this study aimed to assess the clinical effectiveness of a two dose schedule of quadrivalent HPV vaccine compared with the standard three-dose regimen administered at month 0, 2 and 6. We found that with the standard vaccination schedule, completion of the three dose regimen is important to gain maximal protection. However, the effectiveness of two doses increased significantly with increasing time between the doses, and with an interval of approximately 6 months between dose one and two, no differences could be found between two and three doses.
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