Researchers at the Washington University School of Medicine in the US noted that although both Covid-19 and the flu attack the lungs, the former viral disease can also damage other organs.
The latest study, published in The BMJ, shows that Covid-19 was linked with an increased risk of conditions such as acute kidney and liver damage, as well as heart disorders, stroke, severe septic shock, low blood pressure, excessive blood clotting and new-onset diabetes.
“Many high-profile, public comparisons between Covid-19 and the flu have been made; however, those comparisons mostly were drawn using disparate data and statistical methods that have resulted in a lot of conjecture,” said senior study author Ziyad Al-Aly, an assistant professor at Washington University.
“Our research represents an apples-to-apples comparison between the two diseases,” Al-Aly said.
The researchers analysed de-identified medical records in a database maintained by the US Department of Veterans Affairs, the country’s largest integrated health-care delivery system.
They examined information involving 3,641 patients hospitalised in the US with Covid-19 from February 1 through June 17, 2020, as well as 12,676 patients hospitalised with the flu at some point from January 1, 2017, through December 31, 2019.
The average age of patients with either Covid-19 or the flu was 69, the researchers said.
Among patients hospitalised for either Covid-19 or the flu, those infected with the novel coronavirus were nearly five times more likely to die than those with influenza, they said.
The study noted that of the 12,676 patients with flu, 674 (5.3 per cent) died, and of 3,641 patients with Covid-19, 676 (18.5 per cent) died.
On average, the Covid-19 patients were four times more likely to require breathing machines and almost 2.5 times more likely to be treated in the ICU, according to the researchers.
Covid-19 patients were also more likely to be hospitalised for longer, an average of three extra days, they said.
The study also found that there was a higher risk of developing diabetes among Covid-19 patients than flu patients — nine more cases per 100 people.
“These patients didn’t have diabetes until they got Covid-19,” Al-Aly said.
“Then their blood sugar spiked, and they needed huge doses of insulin. Is the 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,” he added.
The finding also showed that the Covid-19 patients most at risk for death were those 75 years old and older who also had chronic kidney disease or dementia, African Americans who were considered medically obese, or who had diabetes or kidney disease.
The researchers also found that, when compared with the flu, Covid-19 was associated with a higher risk of acute kidney damage and severe sepsis shock — both at six more cases on average per 100 hospitalized patients.
Compared with flu patients, people with Covid-19 also required more medications to treat severely low blood pressure, a condition that can lead to organ damage and death –11.5 more people per 100 people, the researchers said.