Mortality at 30 days for respiratory syncytial virus (RSV), human metapneumovirus (hMPV), rhinovirus, or influenza infection is comparable when hospitalization is required, according to study findings published in Influenza and Other Respiratory Viruses.
Investigators compared clinical characteristics and 30-day mortality rates in a large cohort of adult patients hospitalized with a laboratory-confirmed viral respiratory infection (influenza A virus, influenza B virus, RSV, rhinovirus, hMPV, and SARS-CoV-2) from July 1, 2017, to March 1, 2022. The main outcome was 30-day mortality after hospital admission, regardless of hospital admission status at day 30.
Viral testing was conducted routinely in patients with respiratory symptoms from July 2017 through February 2020, the beginning of the COVID-19 pandemic. SARS-CoV-2 was tested routinely in patients with respiratory symptoms from March 2020 until the end of the study.
The analysis included 3504 adult patients who were infected with 1 of the viruses. A peak in incidence in the winter season occurred for influenza A/B and RSV infection, and no season-dependent patterns were observed for the other viruses. The proportion of patients admitted for more than an overnight stay after presenting to the hospital was lowest for those with rhinovirus infections (60%) and comparable for those with influenza, RSV, or hMPV infections (67%-71%).
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[O]nce hospitalisation is required, covariate-adjusted mortality for RSV, hMPV or rhinovirus infections was comparable and not different from mortality following hospitalisation with an influenza A/B virus infection.
Throughout the pandemic, patients with SARS-CoV-2 were more frequently male than female. The lowest proportion of patients without comorbidities occurred from March 2020 to August 2020 (58%).
At 30 days after admission, crude mortality accumulated to 18% for SARS-CoV-2 infections, 9% for influenza A, 11% for influenza B, 10% for RSV, 9% for hMPV infections, and 8% for rhinovirus. Crude SARS-CoV-2 mortality was greater vs all other viruses, although a progressive decrease in mortality during the pandemic was observed (March-August 2020: 25%; September 2020-February 2021: 21%; March-August 2021: 14%; September 2021-February 2022: 14%). The crude mortality among all non-SARS-CoV-2 viruses was similar.
After adjustment, the 30-day mortality odds ratio (OR) for SARS-CoV-2 infection, regardless of pandemic phase, was 2.70 (95% CI, 1.98-3.77) compared with influenza A. No differences occurred for adjusted ORs in 30-day mortality of influenza B, RSV, hMPV infections, and rhinovirus (aOR influenza B: 1.05 [95% CI, 0.67-1.64]; aOR RSV: 1.05 [95% CI, 0.63-1.71]; aOR hMPV: 0.93 [95% CI, 0.54-1.55]; and aOR rhinovirus: 1.00 [95% CI, 0.65-1.52], influenza A as reference). Age was associated with mortality after hospitalization, and an association with comorbidity was not found.
SARS-CoV-2 mortality decreased progressively throughout the pandemic after adjustment. The mortality risk (adjusted OR) was highest from March 2020 to August 2020 and was about a 3-fold decrease from the first phase to the last phase in which data were available (aOR for March 2020-August 2020: 4.92 [95% CI, 3.33-7.33]; aOR for September 2021-February 2022: 1.72 [95% CI, 1.15-2.59], vs influenza A). The adjusted OR for mortality of SARS-CoV-2 infection compared with influenza A was consistently greater during the course of the pandemic.
Among several limitations, no data were available on population prevalence or hospitalization rate per virus. Also, admitting patients with a SARS-CoV-2 virus infection may have been affected by hospital bed availability and chances of survival at the early peak of the COVID-19 pandemic. Furthermore, a mitigating effect of SARS-CoV-2 and/or influenza vaccination in high-risk individuals is possible.
“[O]nce hospitalisation is required, covariate-adjusted mortality for RSV, hMPV or rhinovirus infections was comparable and not different from mortality following hospitalisation with an influenza A/B virus infection,” the investigators noted. “Greater attention for surveillance, development of vaccines, and (antiviral) therapy options for respiratory viruses other than influenza and SARS-CoV-2 seems justified to reduce burden on both health care and the individual,” stated the study authors.
