Summary of the National Advisory Committee on Immunization’s Updated Recommendations on Human Papillomavirus (HPV) vaccines: Nine-valent HPV vaccine and clarification of minimum intervals between doses in the HPV immunization schedule

Human papillomavirus (HPV) infections are the most common sexually transmitted infections, and in the absence of vaccination it is estimated that 75 percent of sexually active Canadians will have an HPV infection at some point in their lives. Quadrivalent (HPV4) and bivalent (HPV2) vaccines have been authorized for use in Canada since 2007 and 2010, respectively. Canada's National Advisory Committee on Immunization (NACI) has previously recommended HPV4 vaccination in males and females according to a three-dose (0, 2, 6 months) or a two-dose (0, 6 months) immunization schedule, or HPV2 vaccination for females according to a three-dose (0, 1,6 months) or a two-dose (0, 6 months) immunization schedule, depending on the age and health status of the recipient. In February 2015, a nine-valent (HPV9) vaccine (Gardasil®9, Merck Canada, Inc.) was authorized for use in Canada for the prevention of HPV types 6-, 11-, 16-, 18-, 31-, 33-, 45-, 52- and 58-related cancers and anogenital warts (AGW) in females aged 9 to 45 years and males aged 9 to 26 years. To summarize evidence on the new HPV9 vaccine and make recommendations for its use in Canada, to review epidemiological data on the relative contribution to disease outcomes of the 5 additional genotypes covered in the HPV9 vaccine, and to clarify acceptable minimum intervals between vaccine doses in either a 2-dose or 3-dose HPV immunization schedule. The NACI HPV working group performed literature reviews on the topics of HPV vaccine minimum dose intervals, and the HPV9 vaccine. Vaccine manufacturers provided additional data for review. All evidence was reviewed, rated, and a representative dataset for each trial was reported in evidence tables. A knowledge synthesis was performed, and NACI approved specific evidence-based recommendations, elucidating the rationale and relevant considerations. At the time of the review, only one published peer-reviewed study of HPV9 vaccine was available for inclusion, but information from additional unpublished studies in the form of presentations, posters, and abstracts were shared by the vaccine manufacturer to be appraised. Based on the evidence available to date, the HPV9 vaccine is recommended on a three-dose schedule for females aged 9 to 26 years; females aged over 26 years who have not been vaccinated previously or who have not completed the vaccination series; and males aged 9 to 26 years. There is insufficient evidence at this time to recommend a two-dose immunization sc