Roughly a year into the pandemic it is clear the new coronavirus is worse than seasonal flu, and a study released outlined just how much worse, showing a death rate almost three times higher among COVID-19 patients. The research, using French national data and published in the journal The Lancet Respiratory Medicine, underscored the increased severity of illness for people with COVID-19.

Researchers compared French national data for 89,530 patients hospitalized with COVID-19 in March and April this year with 45,819 patients hospitalized with seasonal influenza between December 2018 and the end of February 2019. Some 16.9% of hospitalized COVID-19 patients died during the period of study. This compares to a death rate of 5.8% among those with cases of influenza severe enough to require care in a hospital.

Catherine Quantin, a professor at the University Hospital of Dijon and the French national health institute INSERM who jointly led the study, said the difference in death rates was “particularly striking” given the 2018/19 flu season was the deadliest France had seen in five years. The authors note that the difference in the number of hospitalisations, which saw twice as many people admitted for COVID-19 than flu, may be partly explained by existing immunity to influenza, either because of previous infection or vaccination.

U.S. researchers said a big surprise in their study was that COVID-19 patients had a higher risk of developing diabetes, with 9 more cases per 100 than flu patients. “These patients didn’t have diabetes until they got COVID-19,” said study senior author Dr Ziyad Al-Aly, an assistant professor of medicine at Washington University in St. Louis. “Then their blood sugar spiked, and they needed huge doses of insulin. Is diabetes reversible, or will it require long-term management? Will it be type 1 or type 2 diabetes? We just don’t know because COVID-19 barely existed a year ago.” Another finding was that COVID-19 patients had a higher risk of acute kidney damage and severe sepsis shock. For both complications, there was an average of 6 more cases per 100 COVID-19 patients than among flu patients. Also, COVID-19 patients were more likely to need medications to treat severe low blood pressure, a condition that can lead to organ damage and death. The rate was 11.5 more cases per 100 patients than among flu patients.

The authors note that the difference in the number of hospitalisations, which saw twice as many people admitted for Covid-19 than flu, may be partly explained by existing immunity to influenza, either because of previous infection or vaccination. Researchers found that more patients with Covid-19 needed intensive care, 16.3 per cent compared with 10.8 per cent for influenza, while the average stay in ICU was nearly twice as long (15 days compared to 8 days).