Adults hospitalized with omicron die at 1.5 times rate than those admitted with flu: study

Individuals admitted to hospitals with COVID-19 infection died 1.5 times more than those admitted with influenza, according to Swiss researchers.

University of Lucerne researchers examined a national database, extracting information about 3,066 COVID-19 patients admitted to a hospital from January 15 to March 15, 2022. They compared them to patients admitted for influenza A and B from January 1, 2018, to March 15, 2022.

It was an older population and roughly 80% had comorbidities, but fewer COVID patients (13.1%) had respiratory comorbidities than flu patients (24.6%).

“Our results demonstrate that COVID-19 still cannot simply be compared with influenza,” said the study in JAMA Network Open.

Of the COVID patients, 59.1% had gotten at least one dose of vaccine, while 25.3% had gotten three doses. For those with flu, 96.2% had type A, while only 3.8% had type B.

The data come from patients hospitalized primarily for omicron or flu, and researchers found not only a difference in mortality rates but also a higher risk for patients admitted to the ICU with COVID-19. The authors argued that they may have underestimated the severity of omicron outcomes because of more stringent admission screening for COVID as opposed to influenza.

"The question of why these severely ill patients were not admitted to the ICU should be further evaluated. Therefore, our study may underestimate the need for ICU treatment in patients with the SARS-CoV-2 Omicron variant," the researchers wrote.

One of the study’s limitations is that COVID-19 data were gathered at a time when 95% of all COVID cases in Switzerland were caused by the omicron variant B.1.1.529. The gap between the submission of a study to a peer-reviewed journal to its publication poses the possibility that by the time the data are disseminated they might not be totally germane to the present situation, which is one of the reasons preprint studies came to be heavily relied upon during the pandemic.

In the U.S., for instance, the current dominant omicron variant remains XBB 1.5. In Switzerland, the dominant variant is BA.5.

The results come at a time when the U.S. healthcare system has had to battle both respiratory diseases. Influenza in the U.S. has declined precipitously since the end of December, according to the Centers for Disease Control and Prevention (CDC). And incidents of respiratory syncytial virus (RSV) that swamped pediatric hospitals and wards in the U.S. last fall have also decreased steeply.

There appear promising signs regarding COVID-19, as well. According to the Johns Hopkins Coronavirus Resource Center, there were 34,247 new cases of SARS-CoV-2 reported yesterday and 316 deaths. However, experts have warned that one thing that’s predictable about COVID-19 remains its unpredictability. On Feb. 7, Johns Hopkins reported 44,683 new cases of COVID-19 and 552 deaths.

The JAMA Network Open study concluded that “COVID-19 due to the Omicron variant was associated with a higher risk of in-hospital mortality compared with patients with influenza. This indicates that the SARS-CoV-2 Omicron variant should still be taken seriously, and improved prevention and treatment strategies are still highly relevant, although overburdening of the health care system has become less likely over time.”