P-736. Evaluation of virologic rebounds in PLWH after receiving MVA-BN vaccination for mpox

TL;DR

This study examines whether the MVA-BN mpox vaccine causes increases in HIV viral load in people living with HIV, finding rare but notable rebounds in some individuals.

Contribution

The study is the first to investigate virologic rebounds in PLWH after MVA-BN vaccination, identifying a link with prior low-level viremia.

Findings

Eight viral blips and one virologic failure were observed in 74 PLWH after MVA-BN vaccination.

Previous low-level viremia independently predicted virologic rebounds after vaccination.

All rebound events resolved without changes to antiretroviral therapy.

Abstract

The Mpox vaccination with modified vaccinia Ankara-Bavarian Nordic (MVA-BN) has emerged as a critical intervention for preventing disease spread. However, its potential impact on viral load dynamics in people living with HIV (PLWH) remains unclear. This study aims to evaluate whether MVA-BN is associated with the occurrence of virological rebound [(VR), viral blips (VB) or virologic failure (VF)] in PLWH within 6 months following vaccination

Table 1Demographic and clinical characteristics of the study population

Demographic and clinical characteristics of the study population

We enrolled all PLWH who were vaccinated with MVA-BN and had maintained stable virological suppression (target non detectable, TND) for at least 12 months prior to vaccination. Participants were required to be on the same ART for at least 6 months, have at least 200 CD4+ cells/mmc at the time of vaccination, and have at least 1 determination of HIV-RNA within 6 months after completing the vaccination cycle. VB were defined as a single determination of HIV-RNA > 50 cp/mL followed by a determination < 50 cp/mL; VF was defined as a single determination > 1000 cp/mL or at least 2 consecutive measurements > 50 cp/mL. Time to VR was estimated using Kaplan-Meier analysis, and a Cox regression analysis was conducted to evaluate the factors associated with the occurrence of VR

A total of 74 PLWH, all male, were enrolled. The characteristics of the population are summarized in Table1. We observed 8 VB (incidence rate 1.93 per 100 PMFU, 95%CI 0.59 – 3.27), with all events exceeding 100 copies/mL, and 1 VF (incidence rate 0.24 per 100 PMFU, 95% CI 0.00 – 0.71) with 7410 copies/mL. Previous low-level viremia (LLV, defined as at least 2 consecutive measurements > 50 cp/mL and < 200 cp/mL) occurring between 3 and 1 year before vaccination, independently predicted VR after vaccination in a multivariate regression analysis (aHR 13.8; 95%CI 2.2 – 88.0; p = 0.005). For all events, adherence issues were excluded, and all participants returned to a TND status at the subsequent determination without any modifications to their ART regimen

Although rare, the occurrence of VR following MVA-BN in PLWH suggests the need for careful monitoring of HIV-RNA levels after vaccination, especially in individuals with a history of viral load fluctuations. Further research is needed to elucidate the underlying mechanisms and assess the clinical and epidemiological implications

All Authors: No reported disclosures

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