This study is looking at how safe and effective a new Acne vaccine is for adults aged 18 to 45 with moderate to severe acne. Acne is a common skin problem that causes pimples and can affect many people. The vaccine, called an mRNA vaccine, will be tested by giving up to three shots in the arm at different doses. mRNA stands for "messenger ribonucleic acid," which is a type of genetic material used to make vaccines.

The study has two parts: a Core Study and an optional Long-Term Extension (LTE) study. The Core Study will include two groups, each testing different numbers of doses. After finishing the Core Study, some participants will be invited to a follow-up to see how long the vaccine works. Participants from one group might be asked to join another long-term study.

• Participants must have moderate to severe facial acne.
• Some medical conditions and medications can prevent participation.
• The study includes several visits and follow-ups over 30 months.

If you're healthy and interested in trying a new acne treatment, this study might be for you. Please talk to your doctor for more information.