Study reveals waning antibody response to monkeypox vaccine over time

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New investigation to beryllium presented astatine this year's European Congress of Clinical Microbiology and Infectious Diseases (ECCMID 2024) successful Barcelona, Spain (27-30 April) shows that nan antibodies produced by Modified Vaccinia microorganism Ankara - Bavarian Nordic (MVA-BN) vaccination against mpox wane importantly wrong a twelvemonth of receiving nan vaccination – but successful group pinch pre-existing immunity owed to puerility smallpox vaccination successful childhood, antibody levels stay precocious successful almost each cases. The study is presented by PhD student Dr. Marc Shamier, Erasmus MC, Rotterdam, Netherlands, from a investigation squad led by Dr Rory de Vries.

During nan 2022-2023 mpox outbreak, MVA-BN was quickly deployed among at-risk populations, including gay, bisexual, and different men who person activity pinch men (GBMSM). This vaccine is based connected a highly attenuated strain of Vaccinia microorganism (VACV) – a microorganism that belongs to nan orthopoxvirus genus, arsenic do nan viruses that origin smallpox (variola virus) and Mpox (monkeypox virus).

Little is known astir nan longevity of immune responses induced by-MVA-BN vaccination and nan effect of anterior smallpox vaccination. In this study, nan authors assessed nan antibody levels consequence to MVA-BN 1 twelvemonth aft vaccination. While marketed nether various names specified arsenic JYNNEOS, IMVANEX, and IMVAMUNE, each are marque names for nan aforesaid Modified Vaccinia Ankara (MVA)-based vaccine. As such, nan immunological effects they confer are expected to beryllium accordant crossed these products.

Out of nan 118 vaccine recipients, 36 (30%) returned for nan 1-year follow-up visit. Among individuals without pre-existing immunity, 14/21 (67%) had undetectable levels of VACV IgG and a 10.7-fold alteration successful VACV IgG GMT (geometric mean, a modular measurement for antibody levels) was observed compared to nan past clip constituent aft vaccination successful 2022 (4 weeks aft nan 2nd dose) (Figure 1 afloat abstract).

In contrast, among individuals pinch puerility smallpox vaccination, only 1 subordinate retired of 15 (7%) had undetectable VACV IgG aft 1 year, and nan GMT simplification betwixt 4 weeks aft nan past vaccine dose successful 2022 and nan one-year follow-up sojourn was 2.5-fold for those vaccinated pinch 2 doses of MVA-BN, and 1.9-fold for those vaccinated pinch 1 dose of MVA-BN.

The authors say: "A accelerated diminution successful VACV-specific IgG antibodies was observed 1 twelvemonth aft MVA-BN vaccination, starring to nonaccomplishment of detectable antibodies successful 42% (15/36) of nan participants. This simplification was astir pronounced successful individuals without pre-existing immunity. As nan system of protection for mpox remains undefined, nan implications of waning antibody levels for conferring protection stay uncertain."

The authors propose that nan alteration successful antibodies complete clip pursuing MVA-BN vaccination whitethorn beryllium attributable its composition. They say: "The first and second-generation smallpox vaccines contained replication-competent vaccinia virus. MVA-BN is based connected non-replicating virus, which whitethorn effect nan spot and long of nan immune response; pinch nan advantage of a debased consequence of broadside effects."

They add: "Regarding nan imaginable necessity for a booster, it is premature to tie specified conclusions. It is unclear really waning antibody levels subordinate to protection. Immunity besides involves different elements, specified arsenic T-cell responses. Comprehensive objective monitoring complete time, which connects infection rates pinch antibody levels, is required to make informed decisions astir booster vaccination protocols."