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10th International Influenza Meeting

Sep 13 – 15, 2026
University of Muenster (Castle)
Europe/Berlin timezone

Contact/Support: Orgalution GmbH

Longitudinal characterisation of cell-mediated immune responses following influenza A(H5N8) vaccination

Sep 13, 2026, 6:18 PM
1m
Aula (1st floor)

Aula (1st floor)
Poster presentation Antivirals and Vaccines Poster slam

Speaker

Ms Ulla Mikkonen (Institute of Biomedicine, University of Turku, Turku, Finland)

Description

In 2023, Finland experienced a major outbreak of highly pathogenic avian influenza caused by clade 2.3.4.4b influenza A(H5N1) virus, with transmission from wild birds to fur farms. In June 2024, Finland became the first country to vaccinate occupational risk groups using the MF59-adjuvanted influenza A(H5N8) vaccine (A/Astrakhan/3212/2020, Seqirus). We aimed to characterise the quality and durability of cellular immune responses induced by this novel vaccine. Peripheral blood mononuclear cells were collected before vaccination and at 3 weeks, 6 months and 12 months after the second vaccine dose. Antigen-specific T-cell responses were analysed using an activation-induced marker assay following stimulation with overlapping H1, H5 and N8 peptide pools. Vaccine-induced B-cell responses were evaluated using ELISpot assay and flow cytometric detection of H5-specific memory B cells. Robust H5/N8-specific CD4⁺ T-cell responses and relatively weak CD8⁺ T-cell responses were observed. Cellular responses remained detectable 12 months after vaccination. Analyses also indicated induction of H5-specific memory B cells, with declining kinetics during follow-up. The influenza A(H5N8) vaccine induces durable cellular immune responses in individuals at occupational risk of avian influenza exposure. This research provides important information on the durability of influenza A(H5N8) vaccine -induced immunity, which supports future pandemic preparedness and avian influenza vaccine development.

Keywords

Avian influenza, Cellular immunity, Influenza A(H5N8) vaccine

Registration ID INF26- 56
Professional status of the speaker PhD student
Junior scientist status Yes, I am a junior scientist.

Author

Ms Ulla Mikkonen (Institute of Biomedicine, University of Turku, Turku, Finland)

Co-authors

Ms Emilia Peltoniemi (Institute of Biomedicine, University of Turku, Turku, Finland) Mrs Sophie Winter (Institute of Biomedicine, University of Turku, Turku, Finland; InFlames Research Flagship Center, University of Turku, Turku, Finland) Dr Arttu Reinholm (Institute of Biomedicine, University of Turku, Turku, Finland) Dr Milja Belik (Institute of Biomedicine, University of Turku, Turku, Finland) Ms Alina Iakubovskaia (Department of Physiology, University of Helsinki, Helsinki, Finland) Dr Arja Pasternack (Department of Physiology, University of Helsinki, Helsinki, Finland) Prof. Olli Ritvos (Department of Physiology, University of Helsinki, Helsinki, Finland) Ms Oona Liedes (Finnish Institute for Health and Welfare, Helsinki, Finland) Dr Anu Haveri (Finnish Institute for Health and Welfare, Helsinki, Finland) Ms Saimi Vara (Finnish Institute for Health and Welfare, Helsinki, Finland) Dr Merit Melin (Finnish Institute for Health and Welfare, Helsinki, Finland) Dr Pekka Kolehmainen (Institute of Biomedicine, University of Turku, Turku, Finland; InFlames Research Flagship Center, University of Turku, Turku, Finland) Dr Laura Kakkola (Institute of Biomedicine, University of Turku, Turku, Finland; Clinical Microbiology, Turku University Hospital, Turku, Finland) Prof. Ilkka Julkunen (Institute of Biomedicine, University of Turku, Turku, Finland; InFlames Research Flagship Center, University of Turku, Turku, Finland)

Presentation materials

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External references

  • 54

Peer reviewing

Paper

Accepted on by Inga Regling
abstract3573.pdf