New study: Influenza vaccines reduce risk of death among older adults

A new Nordic study led by Statens Serum Institut shows that influenza vaccination during the 2024–2025 winter season reduced the risk of influenza‑related deaths by 63 percent and the risk of hospitalisation by 47 percent among people over the age of 65. The study includes more than 1.1 million older adults from Denmark, Sweden and Finland and has been published in The Lancet Regional Health – Europe.

“This is very positive news, because we know that influenza can be very serious for older people. The results show that the influenza vaccine can, to a large extent, help save lives and spare older people from hospitalisation,” says Anders Hviid, Head of Department at Statens Serum Institut.

Different types of influenza vaccines were used during the season, including enhanced vaccines. These vaccines either contain an adjuvant – a substance that makes the body react more strongly to the vaccine – or a higher dose of antigen to create a stronger immune response. The study shows that the enhanced vaccines provided the best protection. The high‑dose vaccine was associated with 63 percent protection against hospitalisation, while the standard‑dose vaccines used provided 31 and 44 percent protection respectively.

Influenza poses a particular risk to older adults, who account for the vast majority of influenza‑related hospitalisations and deaths, and vaccine effectiveness is generally lower than in younger age groups. The research results point to a significant health benefit when using enhanced vaccines. “The results support that enhanced vaccines should be preferred for older people, where it is cost‑effective,” says Anders Hviid.

The study was carried out with support from the European Medicines Agency and is based on data from Nordic health registries.

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