The safety and efficacy of a 2-dose series for the human papillomavirus vaccines rather than a 3-dose series in older children has not been well defined. This article reviews the literature summarizing the use of all 3 HPV vaccines (2vHPV, 4vHPV, 9vHPV) as a 2-dose series for females and 4vHPV and 9vHPV for males younger than 15 years. Six prospective trials evaluating immunogenicity of a 2-dose series of 2vHPV and/or 4vHPV, as well as an ongoing prospective clinical trial for 9vHPV, are discussed. The 2-dose series with Gardasil 9® in both males and females ages 9 to 14 years appears to be the most widely accepted recommendation. The exact time schedule between the 2 vaccines varies among studies, but it seems that they should be separated by 6 to 12 months. Federal and world-wide organizations' (ie, Centers for Disease Control and Prevention, Food and Drug Administration, and World Health Organization) opinions and recommendations on the appropriate scheduling of the vaccines are also highlighted.
Keywords: Human papillomavirus; human papillomavirus vaccine; pediatrics; sexually transmitted disease.