The goal of this study is to assess the immune response, tolerance, and safety of the low-dose intradermal (forearm) mpox vaccine in people who are HIV+ compared to people who are HIV-, and compared to the standard-dose subcutaneous (upper arm) vaccine. The resulting data will fill knowledge gaps, inform public health practices, and address community concerns about the absence of data for low-dose intradermal mpox vaccinations in people living with HIV.

Inclusion Criteria:

1. Must be able to understand and sign the Informed Consent Form (ICF)

2. ≥18 years of age

   a. Including breastfeeding and pregnant people

3. Must have one or the other of criteria a and b, or can have both:

   1. Planning receipt of (in the next 30 days) or have received the mpox vaccine, and/or
   2. people with recent mpox infection who are out of isolation (≥30 days after symptom onset)

4. Willingness and ability to participate in all study procedures

Exclusion Criteria:

1. Known clinically significant anemia (i.e., Hb < 10 g/dL)
2. Contraindication to phlebotomy based on investigator judgement; e.g., anti-coagulation therapy with history of phlebotomy complications, or clinically significant thrombocytopenia
3. Any condition that, in the opinion of the Investigator, would make study participation unsafe for the individual or would interfere with the objectives of the study

The NYC OSMI observational cohort will be drawn from NYC communities within the broad Vaccine Center catchment area.

The de-identified participant data from the final research dataset used in the published manuscript will be shared upon reasonable request beginning 9 months and ending 36 months following article publication or as required by a condition of awards and agreements supporting the research provided the investigator who proposes to use the data executes a data use agreement with NYU Langone Health. Requests may be directed to: Dr. Mark Mulligan at 877-919-2822. The protocol and statistical analysis plan will be made available on Clinicaltrials.gov only as required by federal regulation or as a condition of awards and agreements supporting the research.

Beginning 9 months and ending 36 months following article publication or as required by a condition of awards and agreements supporting the research.

The investigator who proposed to use the data will be granted access upon reasonable request. Requests should be directed to Dr. Mark Mulligan at 877-919-2822. To gain access, data requestors will need to sign a data access agreement.