Adults hospitalized with the Omicron variant of Covid-19 have a higher death rate than those hospitalized with seasonal flu, even though Omicron is considered less lethal than the Delta and Alpha strains of the same virus, research says. The results of the research will be presented at the European Congress of Clinical Microbiology and Infectious Diseases (April 15-18) in Copenhagen.

In the study of dr. Alaa Atamna and colleagues from the Rabin Medical Center at Belinison Hospital in Israel found that adults who were hospitalized with influenza were 55% less likely to die within 30 days than those who were hospitalized with Omicron.

The study included 167 patients hospitalized with laboratory-confirmed Covid-19 (mean age 71 years, 58% male) and 221 patients with influenza infection (mean age 65 years, 41% male) during December 2021 and January 2022. A total of 63 patients died within 30 days, 19 admitted with influenza (9%) and 44 treated with Omicron (26%).

Respiratory complications and the need for oxygen support and mechanical ventilation were more common in Omicron cases than in seasonal influenza. Also, Omicron patients had more comorbidities, needed more help with activities of daily living, and were more likely to have high blood pressure and diabetes, while asthma was more common in those hospitalized with the flu.

“One possible reason for the higher death rate from Omicron is that patients put on Omicron were older with additional significant underlying diseases, such as diabetes and chronic kidney disease,” says Dr. Atamna adds that an additional difference is that “vaccination against Covid-19 was much lower among Omicron patients.” He notes that “there is one key step people can take that is likely to change the course of both epidemics, get vaccinated for influenza and Covid-19, especially if they are elderly and have underlying medical conditions.”

The authors point out that this is an observational study, so it cannot prove causation, and it was also conducted in a hospital in Israel, so the results may not be applicable to other countries and populations. Finally, the study included only hospitalized patients, so the percentage of hospitalized patients in the total number of infected patients could not be estimated.