Immune Response to MVA-BN and Smallpox Vaccination in Older Adults with or at Risk for HIV
Overview
This study evaluated anti-orthopoxvirus IgG antibody levels in 114 older adults with or at risk for HIV, focusing on responses to MVA-BN vaccination and prior smallpox vaccination. MVA-BN induced sustained IgG responses up to one year regardless of HIV status, while unvaccinated individuals with HIV had lower IgG levels compared to those without HIV.
Background
Monkeypox virus (MPXV) causes mpox, a disease similar to smallpox, with a 2022 outbreak disproportionately affecting men who have sex with men. The Modified Vaccinia Ankara-Bavarian Nordic (MVA-BN) vaccine (JYNNEOS) was deployed during this outbreak to provide protection. Routine smallpox vaccination ended in 1972, leaving many older adults with varying immunity. People with HIV (PWH) are at increased risk of severe mpox, but data on long-term immunogenicity of MVA-BN in this population are limited.
Data Highlights
Characteristic
Value
Number of participants
114
Median age
64 years
Female participants
24.6%
HIV seropositive
46%
MVA-BN vaccinated
20 (17.5%)
Participants with 2 MVA-BN doses
15 (75% of vaccinated)
HIV viral suppression rate
88.5%
Key Findings
MVA-BN vaccination elicited sustained anti-orthopoxvirus IgG antibody levels up to one year post-vaccination regardless of HIV status.
Participants born before 1973 had higher baseline IgG levels, likely reflecting historic smallpox vaccination.
Among unvaccinated individuals, those with HIV had significantly lower IgG levels compared to those without HIV.
Most HIV-positive participants had well-controlled infection with high viral suppression rates.
Limited sample size restricts generalizability but provides important insights into immune responses in a vulnerable, older population.
Clinical Implications
MVA-BN vaccination is effective in inducing durable antibody responses in older adults with or without HIV, supporting its use in this population for mpox prevention. Lower baseline immunity in unvaccinated PWH highlights the need for targeted vaccination efforts. Monitoring antibody levels over time may inform booster vaccination strategies, especially in immunocompromised individuals.
Conclusion
This study demonstrates that MVA-BN vaccination induces sustained orthopoxvirus antibody responses in older adults regardless of HIV status, while historic smallpox vaccination contributes to higher baseline immunity. These findings support continued vaccination efforts in populations at risk for mpox, including those living with HIV.
References
Multicenter AIDS Cohort Study/Women's Interagency HIV Study Combined Cohort Study, 2024 -- Assessment of Immune Reactions to MVA-BN and Previous Smallpox Vaccination in Individuals with HIV or at Increased Risk of HIV Infection
by Yijia Li, Michael B Townsend, Shanshan Li, Quinn E Testa, Tom Medvec, Elizabeth A Thompson, Frank J Palella, Matthew J Mimiaga, James B Brock, Maria L Alcaide, Anandi N Sheth, Michelle Floris-Moore, Aruna Chandran, Audrey L French, Phyllis C Tien, Daniel J Merenstein, Michael Augenbraun, Anjali Sharma, Caitlin A Moran, Charles R Rinaldo, Bernard J C Macatangay, Panayampalli S Satheshkumar, Ken S Ho
