The decision to vaccinate an individual woman should take into account her risk for previous HPV exposure and her potential benefit from vaccination. As with all injectable vaccines, anaphylactic reactions following the administration of the vaccine may occur. Syncope (fainting) may follow any vaccination, especially in adolescents and young adults (vaccinees should be carefully observed for approximately 15 minutes after administration). As with any vaccine, vaccination with HPV may not result in protection in all vaccine recipients. Only protects against diseases caused by HPV types 6, 11, 16 and 18 and to a limited extent against diseases caused by certain related HPV types (precautions against sexually-transmitted diseases should continue to be used). For prophylactic use only; has no effect on active HPV infections or established clinical disease (has not been demonstrated to provide protection against disease from vaccine and non-vaccine HPV types to which a person has previously been exposed through sexual activity). Its use in adult women should take into consideration the variability of HPV type prevalence in different geographical areas. Vaccination is not a substitute for routine cervical screening or anal cancer screening, if it has been recommended by a healthcare provider. Individuals with impaired immune responsiveness may not respond to the vaccine. This vaccine should be given with caution to individuals with thrombocytopenia or any coagulation disorder because bleeding may occur following an intramuscular administration in these individuals. The duration of protection is currently unknown (sustained protective efficacy has been observed for 4.5 years after completion of the 3-dose series; longer term follow-up studies are ongoing). There are no safety, immunogenicity or efficacy data to support interchangeability of this HPV quadrivalent vaccine with other HPV vaccines.