VA study shows COVID more severe than RSV, flu

flu, RSV, COIVD

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A large study of Veterans Affairs (VA) patients in JAMA Internal Medicine shows that, during the 2022 to 2023 season, having COVID-19 was associated with more severe disease outcomes than flu or respiratory syncytial virus (RSV) infection. Differences became less pronounced, however, during the 2023 to 2024 season. 

The study compared outcomes among nonhospitalized veterans who underwent same-day testing and were diagnosed as having either flu, COVID, or RSV from August 1, 2022, to March 31, 2023, or from August 1, 2023, to March 31, 2024. Previous studies on VA cohorts have focused on hospitalized patients and on patients who have not undergone simultaneous testing for all three respiratory viruses. 

Primary outcomes included rates of 30-day hospitalization, intensive care unit admission, and death, as well as the secondary outcome of long-term death extending through 180 days.

Higher COVID death rate for both seasons

A total of 68,581 patients were seen in 2022 to 2023 and 72,939 in the 2023 to 2024 season. In the 2022-23 season 6,239 (9.1%) patients had RSV, 16,947 (24.7%) had influenza, and 4,395 (66.2%) had COVID-19. Those rates were 13.4%, 26.4%, and 60.3%, respectively, during the 2023-24 season.

The median age for patients was 66 (53 to 75) years, and 87.0% were male.

The 30-day risk of death during the 2022 to 2023 season was slightly higher for COVID-19 (1.0%) compared to influenza (0.7%) or RSV (0.7%), but similar during the 2023 to 2024 season (0.9%, 0.7%, and 0.7%, respectively). Mortality risk at 180 days was higher for COVID-19 during both seasons (2023-2024 risk difference [RD] for COVID-19 vs influenza, 0.8% [95% confidence interval [CI], 0.3%to 1.2%]; RD for COVID-19 vs RSV, 0.6% [95% CI, 0.1% to 1.1%]). 

By 180 days, the COVID-19 death rate reached 3.1% in the 2022-23 season and 2.9% in the 2023-24 season. For both seasons, the cumulative incidence of death was highest for COVID-19 throughout follow-up.

In the 2022 to 2023 season, weighted 30-day hospitalizations occurred in 17.5%, 15.9%, and 14.4% of patients diagnosed as having COVID-19, influenza, and RSV, respectively, the authors said. During the 2023 to 2024 season, weighted 30-day hospitalizations occurred in 16.3% of persons diagnosed with influenza, 16.2% diagnosed with COVID-19, and 14.3% with RSV.

Differences in hospitalization and mortality outcomes were primarily found in persons 65 years and older, as well as those who were unvaccinated.

"Differences in hospitalization and mortality outcomes were primarily found in persons 65 years and older, as well as those who were unvaccinated," the authors wrote. 

Vaccination mitigated COVID risk

The authors found that vaccination against COVID-19, however, offset risks of serious disease outcomes. 

"Among groups vaccinated for their respective infections during the 2022 to 2023 season, no difference in 30-day hospitalization risk was found between COVID-19 and influenza," the authors wrote. "No mortality differences between COVID-19 and influenza were found among vaccinated subgroups at any time point through 180 days during either season."

The authors included information only about COVID-19 vaccination, and not seasonal flu vaccination. 

"The higher burden of short-term and long-term adverse outcomes observed with COVID-19 compared with the other RVIs [respiratory viral illnesses] appeared to be attenuated by vaccination, particularly in the 2022 to 2023 season," they concluded. 

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