Comparison of the characteristics, morbidity, and mortality of COVID-19 and seasonal influenza: a nationwide, population-based retrospective cohort study

Abstract

Background To date, influenza epidemics have been considered suitable for use as a model for the COVID-19 epidemic, given that they are respiratory diseases with similar modes of transmission. However, data directly comparing the two diseases are scarce.Methods We did a nationwide retrospective cohort study using the French national administrative database (PMSI), which includes discharge summaries for all hospital admissions in France. All patients hospitalised for COVID-19 from March 1 to April 30, 2020, and all patients hospitalised for influenza between Dec 1, 2018, and Feb 28, 2019, were included. The diagnosis of COVID-19 (International Classification of Diseases [10th edition] codes U07.10, U07.11, U07.12, U07.14, or U07.15) or influenza (J09, J10, or J11) comprised primary, related, or associated diagnosis. Comparisons of risk factors, clinical characteristics, and outcomes between patients hospitalised for COVID-19 and influenza were done, with data also stratified by age group. Findings 89 530 patients with COVID-19 and 45 819 patients with influenza were hospitalised in France during the respective study periods. The median age of patients was 68 years (IQR 52-82) for COVID-19 and 71 years (34-84) for influenza. Patients with COVID-19 were more frequently obese or overweight, and more frequently had diabetes, hypertension, and dyslipidaemia than patients with influenza, whereas those with influenza more frequently had heart failure, chronic respiratory disease, cirrhosis, and deficiency anaemia. Patients admitted to hospital with COVID-19 more frequently developed acute respiratory failure, pulmonary embolism, septic shock, or haemorrhagic stroke than patients with influenza, but less frequently developed myocardial infarction or atrial fibrillation. In-hospital mortality was higher in patients with COVID-19 than in patients with influenza (15 104 [16•9%] of 89 530 vs 2640 [5•8%] of 45 819), with a relative risk of death of 2•9 (95% CI 2•8-3•0) and an age-standardised mortality ratio of 2•82. Of the patients hospitalised, the proportion of paediatric patients (<18 years) was smaller for COVID-19 than for influenza (1227 [1•4%] vs 8942 [19•5%]), but a larger proportion of patients younger than 5 years needed intensive care support for COVID-19 than for influenza (14 [2•3%] of 613 vs 65 [0•9%] of 6973). In adolescents (11-17 years), the in-hospital mortality was ten-times higher for COVID-19 than for influenza (five [1•1% of 458 vs one [0•1%] of 804), and patients with COVID-19 were more frequently obese or overweight.Interpretation The presentation of patients with COVID-19 and seasonal influenza requiring hospitalisation differs considerably. Severe acute respiratory syndrome coronavirus 2 is likely to have a higher potential for respiratory pathogenicity, leading to more respiratory complications and to higher mortality. In children, although the rate of hospitalisation for COVID-19 appears to be lower than for influenza, in-hospital mortality is higher; however, low patient numbers limit this finding...

Characteristics and outcomes of hospital admissions for COVID-19 and influenza in the Toronto area

“…Covariates were selected a priori based on previously reported RESEARCH associations with mortality in COVID-19. 10,[41][42][43] Poisson regression 44 was used for models of mortality, readmission and ICU admission to provide risk ratios and avoid misinterpretation of odds ratios obtained from logistic regression. Negative binomial regression was used for models of hospital length of stay and ICU length of stay.…”

Your health vs. my liberty: Philosophical beliefs dominated reflection and identifiable victim effects when predicting public health recommendation compliance during the COVID-19 pandemic

“…Indeed, as the pandemic death toll rose, some have wondered whether focusing on individual victims could help people better appreciate the threat of the COVID19 pandemic and comply with public health recommendations (Beard, 2020;Graham, 2020;Lewis, 2020). Also, some leaders compared COVID19 to seasonal flus in 2020 despite their public health officials explaining that COVID19 is caused by a different virus, spreads more easily, has a longer period of contagion, causes more serious illness, and is not yet preventable via vaccination (CDC, 2020;Piroth et al, 2020). Some worry that such comparisons to the flu decreased public health compliance and thereby increased COVID19 deaths (Brooks, 2020).…”

Clinical presentation, disease course and outcome of COVID-19 in hospitalized patients with and without pre-existing cardiac disease – a cohort study across eighteen countries

“…A recent large French retrospective cohort study found that the prevalence of MI and atrial fibrillation was lower in patients with COVID-19 than seasonal influenza with a prevalence of 0.6% vs. 1.1% and 12.4% vs. 15.8% respectively. 7 Unfortunately, this study did not report the prevalence of any other cardiac complications, including heart failure and myocarditis. As cardiomyocytes express ACE2 28,29 , the docking receptor of SARS-CoV-2, it has been speculated that SARS-CoV-2 may infect cardiomyocytes, replicate in cardiac tissue and thereby induce direct myocardial damage.…”

“…Coronavirus disease 2019 (COVID-19) has rapidly spread across the globe since December 2019, leading to more than 115 million confirmed cases and 2.5 million fatalities as of the 4 th of March 2021. 1 Although the disease is not as lethal (case fatality ratio (CFR) ∼0.3 – 1%) 2,3 as the Middle-East respiratory syndrome (MERS; CFR ∼35%) 4 and the severe acute respiratory syndrome (SARS; CFR 14 – 15%) 5 , it has become clear that morbidity and mortality is much higher than pandemic influenza (CFR 0.1%) 6,7 , especially among the elderly 3 .…”