Mortality Rate: Severe COVID-19 vs Influenza

In the first year of the pandemic, big studies done in the United States showed that people hospitalized for COVID-19 had nearly 5 times the risk of 30-day mortality compared with those hospitalized for seasonal influenza.

However, investigators wanted to see if this large mortality difference remained throughout the latter years in the pandemic.

A new study looking at mortality of COVID-19 and influenza between October 1, 2022 and January 31, 2023 found the discrepancy in the deaths between the two respiratory illnesses declined. The caveat being many more people are hospitalized with severe COVID-19 as compared to the flu.

“There were 8996 hospitalizations (538 deaths [5.98%] within 30 days) for COVID-19 and 2403 hospitalizations (76 deaths [3.16%]) for seasonal influenza,” the investigators wrote. “Compared with hospitalization for influenza, hospitalization for COVID-19 was associated with a higher risk of death (hazard ratio, 1.61 [95% CI, 1.29-2.02]).”

The study was published in JAMA.

The investigators used the US Department of Veterans Affairs electronic health databases, and they included patients with at least 1 hospital admission record between 2 days before and 10 days after a positive test result for SARS-CoV-2 or influenza and an admission diagnosis for COVID-19 or seasonal influenza. They examined the risk of death using inverse probability-weighted Cox survival models.

“In a VA population in fall-winter 2022-2023, being hospitalized for COVID-19 vs seasonal influenza was associated with an increased risk of death. This finding should be interpreted in the context of a 2 to 3 times greater number of people being hospitalized for COVID-19 vs influenza in the US in this period,” the investigators wrote.

The investigators did report seeing a decline in COVID-19 mortality in the subsequent years of the pandemic, but that influenza death rates remained steadfast throughout.

“The difference in mortality rates between COVID-19 and influenza appears to have decreased since early in the pandemic; death rates among people hospitalized for COVID-19 were 17% to 21% in 2020 vs 6% in this study, while death rates for those hospitalized for influenza were 3.8% in 2020 vs 3.7% in this study,” the investigators wrote.

Most Current Trends
Although COVID-19 mortality has decreased substantially, it still remains responsible for hundreds of deaths each week in the United States. According to the CDC, there was 228 COVID-19 deaths for the 7-day average in its most recent reporting (March 22-28), which is down substantially from 323 deaths the week before—a decline of 29%.

CDC reports the latest 7-day average (March 22-28) for hospitalizations was 2370 for COVID-19, and again this is a decrease from the previous weekly average of 2501.

For the week ending April 1 (week 13), there were 19 reported influenza deaths, the CDC reported.

In the aforementioned JAMA study, the investigators surmised the decline in death rates to a few factors including the change in variants, increased immunity levels due to vaccination and prior infection, and improved care.