To address the raise in Mpox cases, in July 2022, Germany started a pre-exposure or postexposure vaccination programme with the modified vaccinia Ankara virus vaccine (Imvanex/Jynneos).1 As this is a live vaccine, there are constrains for certain patient groups. Current indications for interleukin (IL) 23 antibodies advise against the simultaneous use of live vaccines and recommend a 21-week washout after antibody therapy.2

We report on a 38-year-old HIV-negative man who was receiving treatment with the anti-IL-23 antibody risankizumab (150 mg every 3 months) for psoriasis vulgaris when he was assessed to be at high risk for Mpox. He had not previously received smallpox vaccination and had no additional comorbidities. On balance, rather than wait for the recommended washout period, we decided to offer a first vaccine dose (Jynneos 0.5 mL subcutaneously) 12 weeks after the last antibody dose, and to delay the antibody by 4 weeks. Vaccination was well tolerated apart from a grade 1 injection site reaction that resolved within 2 days. There was no exacerbation of psoriasis vulgaris. After 4 weeks, we offered the second vaccine dose and resumed antibody therapy.

A pre-vaccination immunofluorescence test was weakly reactive for orthopoxvirus IgG and non-reactive for IgM. Four weeks after the first vaccine dose, the IgG titre had increased to 1:320, while the IgM remained undetectable.

Over 30 weeks of follow-up after the last vaccine dose, the patient did not experience symptomatic Mpox.

Using live vaccines in patients on biological therapies requires a thorough risk-benefit evaluation. Few reports of concomitant use can be found in the literature, none regarding Mpox vaccines. In our case, vaccination was well tolerated and led to a seroconversion. Due to lack of comparative data, no conclusion can be made on protective immunity based on the titre. Larger data are needed to guide rational decisions.

Consent obtained directly from patient(s)

This study involves human participants but an independent Research Ethics Committee at the Medical Faculty of the Heinrich-Heine-University of Düsseldorf exempted this study. On behalf of the Ethics Committee there are no ethical or legal concerns regarding the publication of the case report. Comment: According to German law, Ethics Committees evaluate research projects only. A case report is not categorised as a research project but classified as a description of a therapeutical therapy. Participants gave informed consent to participate in the study before taking part.