Antibody response after mpox jab originally developed for smallpox wanes after 6 months

Embargoed until: Publicly released: 2024-10-04 01:30

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US scientists say the mpox antibodies produced by the body after receiving the modified vaccinia Ankara–Bavarian Nordic (MVA-BN) vaccination, originally developed to prevent smallpox, wane after six to 12 months. They looked at antibodies in 22 people who received two doses of the jab and 26 who received one dose and found antibody responses had declined by six to 12 months following vaccination in all the participants. Among those who received two doses, which initially provides 66% protection against mpox, antibody responses at 12 months were similar to or lower than the peak antibody responses in people who received just one dose, which provides just 36% protection against mpox. The findings suggest people vaccinated against mpox more than a year ago may no longer be well protected and should be provided with booster jabs, the authors conclude.

Media release

From: JAMA

Decline of Mpox Antibody Responses After Modified Vaccinia Ankara–Bavarian Nordic Vaccination

About The Study: The modified vaccinia Ankara–Bavarian Nordic (MVA-BN) vaccination generated mpox antibodies that waned by 6 to 12 months. In participants who received 2 doses of MVA-BN vaccine, mpox antibody responses at 12 months were comparable to or lower than peak antibody responses in people receiving 1 dose, which provided limited protection.

Quote from corresponding author Dan H. Barouch, MD, PhD:

“In this observational study, we show that mpox antibody responses decline 6-12 months following Jynneos (MVA-BN) vaccination. Our data suggest that protective immunity may be waning in individuals who were vaccinated with this vaccine in 2022.”

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Journal/
conference: JAMA

Research:Paper

Organisation/s: Center for Virology and Vaccine Research, USA

Funder: The authors acknowledge National Institutes of Health grant CA260476, support from MassCPR (Dr Barouch), and support from NIAID Division of Intramural Research (Dr Moss).

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