Excess all-cause mortality in Norway in 2024.

Aims: The Norwegian Institute of Public Health calculated excess mortality for Norway in 2024 using a reference period that included 2023-a year with significant excess mortality-and concluded there was no excess mortality in 2024. This study estimates excess mortality in 2024 using only pre-pandemic years as the reference, providing a basis for identifying excess COVID-19 related mortality.

Methods: We estimated excess mortality in 2024 using a negative binomial model trained on 2010-2019 data. Deaths were modelled by age (0, 1-19, 20-39, 40-64, 65-79, 80-89 and 90+ years) and sex, with population offsets. Expected mortality was projected using both a conservative approach where the prediction for 2023 was carried forward to 2024 and a non-conservative linear extrapolation to 2024.

Results: The conservative approach estimated 2898 excess deaths (7.0%; 95% prediction interval (PI), 4.9-9.1%) in 2024. Significant excess mortality was observed in age groups 1-19 (45 deaths; 36.6% excess), 20-39 (107 deaths; 17.6% excess), 40-64 (439 deaths; 10.6% excess) and 65-79 (1631 deaths; 13.7% excess). Ages 1-39 and 40-64 accounted for approximately 5% and 15% of total excess mortality, respectively.

Conclusions: Persistent excess mortality from 2022 to 2024 suggests a new elevated mortality baseline and a reduction or reversal of Norway's pre-pandemic mortality decline. Although multiple factors may contribute, given sustained excess mortality since 2022, our findings suggest that the unmitigated spread of SARS-CoV-2 in Norway since 2022 can be associated with increased mortality, particularly for those under 65.