Long-Term Outcomes Following Hospital Admission For COVID-19 Versus Seasonal Influenza: A Cohort Study

Although rates of death and adverse health outcomes following hospital admission for either seasonal influenza or COVID-19 are high, this comparative analysis shows that hospital admission for COVID-19 was associated with higher long-term risks of death and adverse health outcomes in nearly every organ system and significant cumulative excess DALYs than hospital admission for seasonal influenza.

Although COVID-19 had a comparatively higher burden of health loss than seasonal influenza in both the acute and post-acute phase, both COVID-19 and seasonal influenza had a higher burden of health loss in the post-acute phase of infection compared to their respective acute phases, suggesting that hospital admission for either COVID-19 or seasonal influenza has a greater long-term impact on health than the immediately manifested health effects during the acute phase.

Because hospital admission for seasonal influenza was rare in the USA during the COVID-19 group enrolment period, we enrolled a historical seasonal influenza group; 50 509 participants who had a positive influenza test result between Oct 1, 2015, and Feb 28, 2019, were included in the seasonal influenza group.

Finally, we compared COVID-19 with seasonal influenza A and, separately, with all other seasonal influenza viruses, compared to the main approach that evaluated COVID-19 versus all seasonal influenza.

In the COVID-19 group, at 540 days there were cumulatively excess burdens of 1·62 cardiovascular outcomes per 100 persons, 8·00 coagulation and haematological outcomes per 100 persons, 10·93 gastrointestinal outcomes per 100 persons, 4·40 outcomes of fatigue per 100 persons, 3·19 kidney outcomes per 100 persons, 4·28 mental health outcomes per 100 persons, 2·01 metabolic outcomes per 100 persons, 12·24 musculoskeletal outcomes per 100 persons, and 6·38 neurological outcomes per 100 persons.

Over the entire duration of follow-up, hospital admission for COVID-19 in the pre-delta, delta, and omicron eras was associated with a higher risk of death, a higher risk of adverse health outcomes in each organ system except for the pulmonary system, adverse health outcomes across all organ systems, and hospital readmission and admission to intensive care compared to hospital admission for seasonal influenza.

The excess burden per 100 people admitted to hospital for COVID-19 versus seasonal influenza should be interpreted in the context of a two to three times greater number of people being admitted to hospital for COVID-19 versus seasonal influenza in the USA during the same period. 

https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(23)00684-9/fulltext