Study Finds COVID-19 Infection Associated With More Severe Disease Compared With Flu, RSV

During the 2022–2023 respiratory virus season, infection with COVID-19 was associated with more severe disease outcomes than infection with influenza or respiratory syncytial virus (RSV), according to study results published in JAMA Internal Medicine. Investigators noted that the differences between the 3 respiratory infections were not as pronounced during the 2023–2024 season.¹

As of January 24, 2025, the overall respiratory illness activity in the United States is high, according to the CDC. | Image Credit: oz | stock.adobe.com

In the study, investigators aimed to determine the disease severity of the 3 infections among US veterans, using national US Veterans Health Administration electronic health record data for nonhospitalized veterans who underwent same-day testing and were diagnosed with a single infection. Data were included between August 1, 2022, and March 31, 2023, or between August 1, 2023, and March 31, 2024. The primary outcomes included 30-day hospitalization, intensive care unit admission, and death, with secondary outcomes of long-term death extending through 180 days.¹

Investigators include 68,581 individuals in the 2022–2023 cohort, with 9.1% having RSV, 24.7% with influenza, and 66.2% with COVID-19. There were 72,939 individuals in the 2023–2024 cohort, with 13.4% having RSV, 26.4% having influenza, and 60.3% having COVID-19. The data showed that during the 2023–2024 season, the 30-day risks of hospitalization were similar for COVID-19 and influenza, at 16.2% and 16.3%, respectively, and lower for RSV at 14.3%. For 2022–2023 season, the rates were slightly higher for COVID-19 at 1% compared with 0.7% for both influenza and RSV.¹

The 180-day mortality risk was higher for COVID-19 for both seasons, specifically among veterans who did not receive the COVID-19 vaccination in the previous year. Further, they noted that there were no mortality differences at any time between COVID-19 and influenza among the groups that were vaccinated for the respective infections, according to the study authors.¹

As of January 24, 2025, the overall respiratory illness activity in the United States is high, according to the CDC. For emergency department visits, COVID-19 is having a slight decrease and RSV is moderately decreasing. However, influenza is having a very high decrease. The rates of COVID-19 are still elevated in the US, and the emergency department (ED) visits and hospitalizations are highest for older adults, but ED visits are also elevated for young children. Currently, influenza activity remains elevated and is increasing across the country, but RSV has peaked in many areas. ED visits and hospitalizations for RSV are highest in children, and hospitalizations are elevated for older adults as well. As for wastewater viral activity, the levels for flu are high compared with only moderate for COVID-19 and RSV.²

The CDC also notes that vaccination coverage for the 2024–2025 season is low for influenza and COVID-19 among adults and children. However, the coverage of COVID-19 vaccines has increased for older adults compared with last season. RSV vaccinations remain low for US adults, the agency adds. The estimates for respiratory viruses this season will either be similar or have lower peak numbers of hospitalizations compared with last year; however, peak hospitalizations from all respiratory viruses remain higher than before the emergence of COVID-19.²

REFERENCES

1. Bajema KL, Bui DP, Yan L, et al. Severity and Long-Term Mortality of COVID-19, Influenza, and Respiratory Syncytial Virus. JAMA Intern Med. Published online January 27, 2025. doi:10.1001/jamainternmed.2024.7452

2. CDC. Respiratory Illnesses Data Channel. Updated January 24, 2024. Accessed January 30, 2025. https://www.cdc.gov/respiratory-viruses/data/index.html