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The following is a summary of “Long-term outcomes following hospital admission for COVID-19 versus seasonal influenza: a cohort study,” published in the March 2024 issue of Infectious Diseases by Xie et al.

Earlier studies comparing individuals hospitalized for COVID-19 versus influenza examined the likelihood of death, readmission to the hospital, and a restricted set of health outcomes within six months after infection.

Researchers conducted a retrospective study to compare the short-term and long-term health risks and impacts associated with hospitalization for COVID-19 and seasonal influenza.

They conducted a cohort study utilizing the US Department of Veterans Affairs healthcare databases, analyzing data from 81,280 individuals hospitalized for COVID-19 (March 1, 2020, to June 30, 2022) and 10,985 individuals hospitalized for seasonal influenza (Oct 1, 2015, to Feb 28, 2019). Over an 18-month follow-up, participants were assessed for risks and burdens, including death, 94 specific health outcomes, ten organ systems, overall organ system burden, readmission, and intensive care admission. Baseline characteristics were balanced using inverse probability weighting, and Cox and Poisson models were employed to estimate relative and absolute risks, measured as event rates and disability-adjusted life-years (DALYs) per 100 persons.

The results showed that over an 18-month follow-up period, compared to seasonal influenza, individuals with COVID-19 had a higher risk of death (hazard ratio [HR] 1.51 [95% CI 1.45–1.58]), resulting in an excess death rate of 8.62 (95% CI 7.55–9.44) per 100 persons in the COVID-19 group compared to the influenza group. Comparative analyses of 94 predetermined health outcomes revealed that COVID-19 was associated with a higher risk for 68.1% (64 of 94) of these outcomes. 

In comparison, seasonal influenza was associated with a higher risk for only 6.4% (six out of 94) of outcomes, including three out of four predefined pulmonary outcomes. When examining organ systems, COVID-19 showed a higher risk across all systems except for the pulmonary system, where the risk was higher in seasonal influenza. Adverse health outcomes across all organ systems occurred at rates of 615.18 (95% CI 605.17–624.88) per 100 persons in COVID-19 and 536.90 (95% CI 527.38–544.90) per 100 persons in seasonal influenza, translating to an excess rate of 78.72 (95% CI 66.15–91.24) per 100 persons in COVID-19. The total number of DALYs across all organ systems was 287.43 (95% CI 281.10–293.59) per 100 persons in the COVID-19 group and 242.66 (95% CI 236.75–247.67) per 100 persons in the seasonal influenza group, indicating 45.03 (95% CI 37.15–52.90) higher DALYs per 100 persons in COVID-19. Decomposition analyses revealed that in both COVID-19 and seasonal influenza, there was a higher burden of health loss in the post-acute phase compared to the acute phase. Furthermore, except for the pulmonary system, COVID-19 resulted in a higher burden of health loss across all other organ systems than seasonal influenza in both acute and post-acute phases. Compared to seasonal influenza, COVID-19 showed an increased risk of hospital readmission (excess rate 20.50 [95% CI 16.10–24.86] per 100 persons) and admission to intensive care (excess rate 9.23 [95% CI 6.68–11.82] per 100 persons). These findings remained consistent when evaluating risks by individuals’ vaccination status and those admitted to hospital during the pre-delta, delta, and omicron eras.

Investigators concluded that COVID-19 survivors, compared to seasonal flu survivors, face a higher risk of death and long-term health issues across various organs, highlighting the need for more robust prevention and long-term care for both illnesses.

Source: thelancet.com/journals/laninf/article/PIIS1473-3099(23)00684-9/fulltext#seccestitle160