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According to a study published online over a 2-month period, about twice as many patients were admitted to hospitals in France for COVID-19 over a 2-month period than were admitted for seasonal influenza over a 3-month period the previous year. The Lancet Respiratory Medicine.
In-hospital mortality was nearly three times higher for COVID-19 than for seasonal flu, researchers found. In addition, patients with COVID-19 were more likely to receive invasive mechanical ventilation (9.7% versus 4%) and had an average longer stay in the ICU (15 days versus 8 days).
SARS-CoV-2 appears to have a higher potential for respiratory pathogenicity, leading to more respiratory complications in patients with less co-morbidity, and is associated with a higher risk of mortality, especially in adolescents, although all conclusions for this age group are cautious given the small number of deaths, ”write Lionel Piroth, MD, PhD, of the Infectious Diseases Department, Dijon University Hospital, Dijon, France, and colleagues.
The study “is the largest to date to compare the two diseases and confirms that COVID-19 is much more severe than the flu,” said study author Catherine Quantin, MD, PhD, in a press release. “The finding that the death rate in COVID-19 was three times higher than in seasonal flu is particularly striking when we recall that the 2018/2019 flu season was the worst in France in the last five years in terms of deaths,” continued Quantin, who led the research together. She is affiliated with the University Hospital of Dijon and Inserm.
The researchers analyzed data from a national database and compared 89,530 COVID-19 hospitalizations between March 1 and April 30, 2020, with 45,819 hospital admissions with seasonal flu between December 1, 2018 and February 28, 2019.
The death rate was 16.9% in patients admitted to hospital with COVID-19, compared to 5.8% in patients admitted to hospital with the flu.
Fewer patients under the age of 18 were hospitalized with COVID-19 than with seasonal influenza (1.4% vs 19.5%; 1227 vs 8942), but a higher proportion of those under 5 years of age required intensive care for COVID -19 (2.9% vs 0.9%). The mortality rate in children less than 5 years of age was similar for both groups (0.5% versus 0.2%).
Among patients 11–17 years old, 5 of 548 (1.1%) patients with COVID-19 died, compared to 1 of 804 (0.1%) patients with flu.
Test methods for influenza likely varied from hospital to hospital, while testing for COVID-19 may have been more standardized. This could be a limitation of the study, the researchers note. In addition, flu seasons vary from year to year and flu cases may depend on vaccination coverage and the remaining immunity of the population.
“The large sample size is a major strength of the study and it is believed that the indication for hospitalization was the same in the two periods and thus does not bias the results,” writes Eskild Petersen, MD, DMsc, in an accompanying note. the study. “The results … clearly show that COVID-19 is more severe than seasonal flu.”
In addition, this study and previous research show that “COVID-19 is not a harmless infection in children and adolescents,” said Petersen, who is affiliated with Aarhus University in Denmark and the European Society for Clinical Microbiology and Infectious Diseases Emerging Infections Task Force .
The study was funded by the French National Research Agency. Two authors have different financial ties with different pharmaceutical companies, details of which are available in the journal article. Petersen has not disclosed any relevant financial relationships.
Lancet Respir Med. Published online December 17, 2020. Summary, commentary
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