All about seasonal influenza

Overall, the 2023-2024 influenza season was of low-to-moderate magnitude, had a protracted course, with influenza A(H1N1) dominating also this season, but cocirculating with A(H3N2) viruses and with much less influenza B/Victoria-lineage viruses.

Information note about vaccine against seasonal influenza. The publication contains information about risk groups and health benefits of influenza vaccination.

During the 2023-24 season, both A(H1N1) 5a.2a and 5a.2a1 viruses circulated, with a slightly higher prevalence of the 5a.2a1 during the winter outbreak. The A(H3N2) viruses have been mainly from the 2a.3a.1 clade, with J.1 during the winter and J.2 the latest months.

Almost 1.6 million people in Norway belong to groups with an increased risk of complications from influenza. They are recommended to take the seasonal influenza vaccine.

Pregnant women are at increased risk of a severe influenza disease course. Pregnant women in their 2nd and 3rd trimesters should take the influenza vaccine. Women in the 1st trimester with other additional risk factors are also recommended to take the vaccine.

Anyone can become seriously ill from influenza, but certain risk groups are more susceptible to a severe disease course than others. The health benefits can be considerable if people in these risk groups are vaccinated.

The 2022-23 season started early, crossing the outbreak threshold of 10 % positives in week 48 (sentinel)/week 49 (comprehensive) and had a sharp first peak in weeks 51-52/2022 with 46 % positives in the sentinel and 25 % positives in the comprehensive surveillance.

The current season started early with outbreak threshold of 10 % positives in week 48 (sentinel)/week 49 (comprehensive) and had a sharp first peak in weeks 51-52/2022 with 46 % positives in the sentinel and 25 % positives in the comprehensive surveillance.

The background for this project is our lack of knowledge about the causes of childhood cancer.

Influenza causes fever and body aches as well as respiratory symptoms. Typically, five to ten per cent of the population becomes ill during a winter season. Influenza seasons vary in severity.

The WHO National Influenza Centre Norway at the NIPH prepares a report for WHO every February and September that describes the influenza situation in Norway.

The poster ”Good habits to prevent influenza” focuses on cough- and hand hygiene to prevent infection with influenza. It can be ordered for use where information to the public is required in English.