#17,881
While it is apparent that - due to increased immunity from vaccination and/or infection, and changes in the SARS-CoV-2 virus - that COVID's fatality rate has dropped significantly since 2020, it continues to infect millions of people each month, hospitalizing (and killing) thousands.
Roughly 80% of countries no longer regularly report COVID infections, hospitalizations, or deaths to the WHO, yet in their latest monthly epidemiological update they report:
Many countries have adopted the attitude that COVID infection is now comparable to influenza in terms of severity, but studies continue to suggest that morbidity and mortality from the SARS-CoV-2 virus still exceeds that of seasonal flu.
There are also studies that show that long-term sequelae (aka `Long COVID') is more frequent, and more severe than with other post-viral syndromes from respiratory illnesses (see NIH Preprint: Comparing The Impact Of `Long Flu' to `Long COVID').
While most people use Influenza A as the benchmark for comparison, over the years we've seen evidence that other common respiratory infections (including Influenza B, RSV, metapneumovirus, etc.) may have equally severe outcomes.
ERJ: When “B” becomes “A” : The Emerging Threat of Influenza B Virus
California: Orange County Declares Public Health Emergency Over Rise In Pediatric RSV
CDC HAN #00473: Severe Respiratory Illnesses Associated with Rhinoviruses and/or Enteroviruses Including EV-D68 – Multistate, 2022
But the lack of testing and reporting on all of viral infections makes direct comparisons difficult. While far from perfect, one compromise is to study outcomes in those who are sick enough to be hospitalized. Which is exactly what today's study does.
Based on 30-day outcomes among hospitalized patients, researchers found that the risks of death from Influenza A, Influenza B, RSV, and metapneumovirus were roughly comparable, and that even after the arrival of Omicron (spring 2022), COVID continued to carry a 70% higher case fatality rate (CFR) than influenza A.
This study is subject to a number of limitations (see full text), but it does illustrate that in addition of influenza A and COVID, other common viral illnesses can produce significant morbidity and mortality in the hospitalized patient.
I've reproduced the abstract and some excerpts, but you'll want to follow the link to read it in its entirety.
ORIGINAL ARTICLE
Open Access
Comparative analysis of mortality in patients admitted with an infection with influenza A/B virus, respiratory syncytial virus, rhinovirus, metapneumovirus or SARS-CoV-2Abstract
Background
While influenza virus and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are recognised as a cause of severe illness and mortality, clinical interest for respiratory syncytial virus (RSV), rhinovirus and human metapneumovirus (hMPV) infections is still limited.
Methods
We conducted a retrospective database study comparing baseline characteristics and 30-day mortality in a large cohort of adult patients admitted for an overnight stay or longer with an influenza virus (A/B), rhinovirus, hMPV, RSV or SARS-CoV-2 infection. For non-SARS-CoV-2 viruses, data were included for the period July 2017–February 2020. For SARS-CoV-2, data between March 2020 and March 2022 were included.
Results
Covariate-adjusted 30-day mortality following RSV, hMPV or rhinovirus infections was substantial (crude mortality 8–10%) and comparable with mortality following hospitalisation with an influenza A virus infection.
Mortality following a SARS-CoV-2 infection was consistently higher than for any other respiratory virus, at any point in time (crude mortality 14–25%). Odds of mortality for SARS-CoV-2 compared with influenza A declined from 4.9 to 1.7 over the course of the pandemic. Patients with SARS-CoV-2 infection had less comorbidity than patients with other respiratory virus infections and were more often male. In this cohort, age was related to mortality following hospitalisation, while an association with comorbidity was not apparent.
Conclusions
With the exception of SARS-CoV-2 infections, we find the clinical outcome of common respiratory virus infections requiring hospitalisation more similar than often assumed. The observed mortality from SARS-CoV-2 was significantly higher, but the difference with other respiratory viruses became less distinct over time.
(SNIP)
The aim of this study was to provide a comparative analysis of 30-day mortality following hospitalisation with an infection with influenza A/B, RSV, rhinovirus, metapneumovirus or SARS-CoV-2.
In this retrospective cohort study, we found that, once 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 year, RSV, rhinovirus and hMPV infections made up a substantial proportion of total respiratory virus infections requiring hospitalisation. RSV is increasingly recognised as a cause of severe illness and mortality in high-risk older adults,4, 5, 18-20 while clinical interest for rhinovirus and hMPV infections is still limited. In our study, 30-day mortality was not different between influenza and RSV, hMPV or rhinovirus infections (8–10%) and in line with previously published influenza and RSV data on adults.4, 21, 22
Lower mortality rates have been reported by some6, 23 and might be explained by a shorter follow-up time when in-hospital mortality rather than 30-day mortality is used as an outcome, or by less stringent criteria for hospital admission. In line with the general consensus, we found that elderly are particularly vulnerable for poor outcomes of respiratory virus infections.2, 20, 24 In our dataset, however, comorbidity registered as CCI was not associated with mortality following hospitalisation with a respiratory virus infection. This may seem in contrast to other findings;25-27 however, this discrepancy might in part be explained by a mitigating effect of influenza vaccination in high-risk individuals, or by a lower admission threshold for those with expected severe progression of disease.
Few studies have compared SARS-CoV-2 mortality during winter 2021/2022 with mortality following hospitalisation with several other common respiratory virus infections. In the last half year of the study period (1 September 2021 to 1 March 2022), odds of mortality following hospitalisation with a SARS-CoV-2 infection were 1.7 times greater than following an influenza virus infection.
