Neutralizing Antibody Responses to Mpox Persist Up to 9 Months After Intradermal MVA-BN Vaccination
Overview
This prospective cohort study in Sweden evaluated monkeypox virus (MPXV) neutralizing antibody kinetics up to 9 months following intradermal MVA-BN vaccination in men who have sex with men. Antibody titers waned significantly at 3 and 9 months post-vaccination, with smallpox vaccination history influencing responses. The findings highlight the need for further research on booster dosing and immunological memory.
Background
The 2022 global mpox outbreak disproportionately affected men who have sex with men (MSM), prompting vaccination efforts with the Modified Vaccinia Ankara–Bavarian Nordic (MVA-BN) vaccine. Sweden implemented a dose-sparing intradermal regimen, administering either two 0.1 mL doses or a single dose for those previously vaccinated against smallpox. Previous studies have reported low MPXV-neutralizing antibody titers post-vaccination and comparable effectiveness between intradermal and subcutaneous routes. Understanding antibody persistence is critical for optimizing vaccination strategies amid limited global vaccine supplies.
Data Highlights
Timepoint
Neutralizing Antibody Titer
Notes
Pre-vaccination
Baseline low or undetectable
Excluding suspected prior infections
1 month after first dose
Significant increase in titers
Measured in smallpox-unvaccinated and vaccinated groups
1 month after full vaccination
Peak titers observed
Two doses for unvaccinated, one dose for previously vaccinated
3 months after full vaccination
Significant waning of titers
Paired Wilcoxon signed-rank test confirmed decline
9 months after full vaccination
Further decline in titers
Neutralizing antibodies persist but at reduced levels
Key Findings
Neutralizing antibodies against MPXV increased significantly 1 month after vaccination but waned at 3 and 9 months.
Smallpox vaccination history was the only significant covariate influencing antibody titers in mixed-effects models.
Both single-dose (for previously smallpox-vaccinated) and two-dose (for unvaccinated) intradermal MVA-BN regimens induced measurable neutralizing antibodies.
Six participants were excluded due to suspected prior asymptomatic infection or hybrid immunity based on baseline titers.
Neutralizing antibody titers post-intradermal vaccination were consistent with previous reports following subcutaneous vaccination.
Clinical Implications
Clinicians should be aware that neutralizing antibody levels after intradermal MVA-BN vaccination decline substantially by 3 to 9 months, which may impact long-term protection. Smallpox vaccination history should be considered when assessing immune responses. These findings support the potential need for booster doses and further evaluation of immunological memory to optimize mpox vaccination strategies in at-risk populations.
Conclusion
Intradermal MVA-BN vaccination induces neutralizing antibodies against MPXV that persist up to 9 months but decline significantly over time. Further studies are warranted to determine the role of booster doses and long-term immunity.
References
Article Source 2024 -- Neutralizing Antibody Responses to Mpox Persist for Up to 9 Months After One or Two Doses of Intradermal MVA-BN Vaccination in Sweden
by Carmen Espinosa-Gongora, Wanda Christ, Núria Mayola Danés, Claudia Eichler-Jonsson, Finn Filén, Elisabet Storgärd, Victor Westergren, Jonas Klingström, Sara Gredmark-Russ, Kari Johansen, Anna Mia Ekström, Klara Sondén
