This observational study has been designed to characterize humoral and cellular immune responses after vaccination against monkeypox (MKP) in HIV positive and negative individuals at high risk of MKP infection during the vaccination campaign in the current monkeypox outbreak.

Of the 23,837 cases of monkeypox reported in the European Region of the WHO, 7.037 have been identified in Spain, according to the National Epidemiological Surveillance Network (RENAVE). Most of diagnosed individuals are men born in Spain, being nearly 40% HIV positive. The clinical evolution was satisfactory, although 3-7% of cases required hospitalization.

Given the limited number of available doses of the MVA-BN vaccine, it has been recently approved its use as a single intradermal dose. However, this posology can be more reactogenic than subcutaneous injection and there is limited data on its immunogenicity and effectiveness in people living with HIV (PLWH), which account for about half of the monkeypox cases in the current outbreak.

The present observational study has been designed to investigate the humoral and cellular immune responses following monkeypox vaccination in PLWH.

Inclusion Criteria:

1. Adult individuals of ≥18 years old.
2. Willing to comply with the requirements of the protocol and available for follow-up for the planned duration of the trial.
3. Has understood the information provided and capable of giving informed consent.

Exclusion Criteria:

1. Participant has any medical condition and/or finding that in the investigator opinion might increase participant risks, interfere with the study or impair interpretation of study data.

100 individuals who have been/will be vaccinated against MKP as pre-exposuire profilaxis following the National Vaccination Plan (40-50/50-60% of HIV negative and HIV positive individuals)