Immunity From Mpox Vaccine May Be Waning

FRIDAY, Oct. 4, 2024 (HealthDay News) -- Immunity against mpox may be waning for those vaccinated with the modified vaccinia Ankara-Bavarian Nordic (MVA-BN; Jynneos) vaccine, according to a research letter published online Oct. 3 in the Journal of the American Medical Association.

Ai-ris Y. Collier, M.D., from the Beth Israel Deaconess Medical Center in Boston, and colleagues assessed mpox-specific immune responses for 12 months after MVA-BN vaccination. The analysis included serum specimens from a convenience sample of adults who received the MVA-BN vaccine (26 with one dose and 22 with two doses) or who had a confirmed diagnosis of mpox infection (three individuals) during the 2022 outbreak.

The researchers found that in participants who received two doses of the vaccine, median binding antibody enzyme-linked immunosorbent assay (ELISA) titers to mpox M1R, B6R, A35R, A29L, and H3L antigens, respectively, were 28, 25, 25, 27, and 27 at baseline, peaked at 112, 384, 85, 29, and 76 at week 3 after vaccination, and then declined to 38, 82, 32, 25, and 31 at 12 months. With one vaccine dose, the median binding antibody ELISA titers to mpox M1R, B6R, A35R, A29L, and H3L antigens peaked at 45, 90, 32, 31, and 28, respectively, at week 3, but then declined to 33, 43, 30, 25, and 28, respectively, at 12 months. After either one or two doses, mpox serum neutralizing antibody titers were minimal at three months. However, after natural infection, high titers of mpox neutralizing antibodies were detected at three months and persisted nine months after infection.

"These data suggest that protective immunity may be waning in individuals who were vaccinated with MVA-BN in 2022 and that boosting may be required to maintain robust levels of protective immunity," the authors write.

One author disclosed ties to the pharmaceutical industry.

Abstract/Full Text