1495. Mpox Vaccine Immunity in People Living with HIV (PLWH) During The 2022 Mpox Outbreak in New York City
Authors: Kottkamp Angelica C , Oom Aaron , Wilson Kesi K , Rettig Stephanie , Frank Olivia , Engelson Celia , Davis Tamia S , Noriega Irma , Callahan Jacqueline , Yip Samantha , Youn Heekoung , Wagner Julia , Carmody Ellie , Parameswaran Lalitha , Tuen Michael , Wilson Jimmy P , Goins Shelby J , Zhao Lisa , Nweke Samuel , Haiken Sarah , Suman Pamela , Dontino Amanda , Rosen Jennifer , Zucker Jane R , Duerr Ralf , Samanovic Marie I , Mulligan Mark J 
Published: November 2023

Abstract

Background
The WHO estimated that in 2022 49% of people affected by Mpox were PLWH. Due to initial vaccine shortage in 2022, a 1/5 dose of vaccine given intradermally (ID) was FDA-authorized (8/9/22). The ID regimen had never been evaluated in PLWH. Here we describe the characteristics, and IgG responses of Mpox vaccination in PLWH and HIV-negative participants.

Methods
We are conducting a longitudinal, observational study of adults with and without HIV who received the JYNNEOS vaccine or had Mpox infection in NYC. Clinical, demographic information, and Mpox H3L-specific serum IgG titers are assessed.

Results
145 participants are enrolled: 25% are PLWH (median CD4 685 cells/mm3), 14% had Mpox disease and 21% had prior smallpox vaccination. 71% with Mpox disease were PLWH. The cohort is racially/ethnically diverse, mostly men (81%) and LGBTQ+ (90%). A third of the participants were recruited from NYC DOHMH pop-up vaccination site (34%), followed by peer or professional referral (20% & 19%). Routes of vaccination were: SC-ID (49%), ID-ID (21%), SC-SC (20%), and ID-SC (10%). Redness (37%) & swelling (21%) at site of injection were common reactions. Prior smallpox vaccination was associated with higher and sustained IgG titers even after one vaccine dose. Excluding such participants, antibody titers start declining post-dose 2 (antibody half-life of 103 days). There was no difference in IgG titers at 3 months post-dose 2 between PLWH and HIV-negative for ID or any other route. Titers at 3 months post-dose 2 in PLWH correlated with CD4 counts. Longer interval between the two doses contributed to higher titers. Mpox infection yielded to significantly higher titers than vaccination post-dose 1, but no after 2 doses.

Conclusion
Our study highlights the disproportionate burden of Mpox infection on PLWH. A diverse population representative of those most affected by 2022 Mpox was recruited. The vaccine, whether ID or SC, was well tolerated in PLWH and HIV-negative. More than two-thirds of participants with Mpox disease were PLWH. Individuals with prior smallpox vaccination maintain strong antibody levels post-dose 2, however, levels decline in individuals with no anterior prime. Our preliminary results show no negative impact of the ID dose regimen on antibody levels in PLWH.

Disclosures
Ellie Carmody, MD, MPH, AstraZeneca: Stocks/Bonds|Merck: Stocks/Bonds Lalitha Parameswaran, MD, MPH, Pfizer: Grant/Research Support Mark J. Mulligan, M.D., Lilly: Grant/Research Support|Meissa Vaccines, Inc.: Advisor/Consultant|Meissa Vaccines, Inc.: Board Member|Merck: Advisor/Consultant|Merck: Board Member|Pfizer: Advisor/Consultant|Pfizer: Board Member|Pfizer: Grant/Research Support|Sanofi: Grant/Research Support