Efficacy Against Oral Persistent Infection, Immunogenicity and Safety of the 9-valent Human Papillomavirus Vaccine (9vHPV) in Men Aged 20-45 Years (V503-049)

To join this study, you need to be a healthy man between 20 and 45 years old. You must be able to understand the study information and be willing to give your permission to take part. It's also important that you can be contacted easily for follow-up appointments and have had at least one sexual partner in your lifetime.

However, there are reasons why you *wouldn't* be able to join. For example, if you've ever had certain HPV-related health problems like anal lesions or head and neck cancer, or if you have visible signs of HPV or other sexually transmitted infections. You also can't take part if you're allergic to any vaccine ingredients, have issues with blood clotting, or if your immune system isn't working properly.

If you join this study, you will receive either the HPV vaccine or a placebo (a dummy injection) over a series of three doses. The study team will check your health at the start and throughout. You'll have regular check-ups, and the researchers will collect samples, likely to check for HPV infection and how your body is responding to the vaccine. You'll also be asked to complete some reports yourself. The total duration of participation isn't specified but typically involves several visits over many months to a few years to track long-term effects.