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The following is a summary of “Hospital and mortality burden of COVID-19 compared with influenza in Denmark: a national observational cohort study, 2022–24,” published in the January 2025 issue of Infectious Disease by Bager et al. 

Researchers conducted a retrospective study to evaluate the hospital admissions and mortality burden of COVID-19 and compare it with influenza in Denmark from May 2022 to 2024.  

They assessed residents in Denmark from May 16, 2022, to June 7, 2024, using national registries. Data included admissions for COVID-19 or influenza (defined as a positive PCR test for either virus within 14 days before and 2 days after hospital admission), deaths, sex, age, vaccination status, comorbidities, and long-term care facility residency. Negative binomial regression was used to calculate adjusted incidence rate ratios (aIRRs) comparing hospital admission rates between COVID-19 and influenza. Kaplan–Meier estimators were used to generate cumulative incidence curves and to assess severity, adjusted risk ratios (aRRs) of 30-day mortality were calculated for COVID-19 and influenza hospitalizations.  

The results showed that among 58,991,70 individuals, COVID-19 admissions (n=24,400) were more frequent than influenza admissions (n=8,385; aIRR 2.04 [95% CI 1.38–3.02]). This trend was observed particularly in the first year (May 2022 to May 2023) compared to the second year (May 2023 to June 2024; P =0.0096), during summer vs winter (P <0.0001), and in individuals aged 65 or older vs those younger than 65 years (P <0.0001), COVID-19 patients also had higher mortality (n=2,361) compared to patients with influenza (n=489; aIRR 3.19 [95% CI 2.24–4.53]). Among winter admissions (n=19,286), COVID-19 mortality risk was higher than influenza (aRR 1.23 [95% CI 1.08–1.37]), especially for those unvaccinated for both diseases (1.36 [1.05–1.67]), with comorbidities (1.27 [1.11–1.43]), and males (1.36 [1.14–1.59]).  

Investigators concluded the COVID-19 illustrated a greater disease burden than influenza, with more hospitalizations, deaths, and severe cases, among the unvaccinated, those with comorbidities, and males, emphasizing the ongoing need for public health efforts to mitigate SARS-CoV-2’s impact. 

Source: thelancet.com/journals/laninf/article/PIIS1473-3099(24)00806-5/fulltext