How Do Outcomes Compare Between Patients Hospitalized with COVID-19 and Those With Influenza?
Authors:
News Author: Lisa O’Mary; CME Author: Charles P. Vega, MD
Faculty and Disclosures
Released: 3/24/2023
Note: The information on the coronavirus outbreak is continually evolving. The content within this activity serves as a historical reference to the information that was available at the time of this publication. We continue to add to the collection of activities on this subject as new information becomes available. It is the policy of Medscape Education to avoid the mention of brand names or specific manufacturers in accredited educational activities. However, manufacturer names related to the approved COVID-19 vaccines are provided in this activity in an effort to promote clarity. The use of manufacturer names should not be viewed as an endorsement by Medscape of any specific product or manufacturer.
Clinical Context
The COVID-19 pandemic has shifted considerably since the advent of the Omicron variant at the end of 2021. It is clear that Omicron more effectively eludes the primary SARS-CoV-2 vaccination series compared with previous variants, which prompted the development of 2 bivalent booster vaccines designed to improve activity against Omicron. But how effective have these bivalent boosters been? A recent study by Lin and colleagues, published in the February 23, 2023, issue of the New England Journal of Medicine, addressed this issue.[1]
Researchers had access to a large cohort of more than 6 million individuals living in the US from September 1 to November 3, 2022; 17.0% of eligible patients received the bivalent booster. Booster effectiveness against severe infection peaked at 4 weeks and then waned thereafter. The rates of vaccine effectiveness against severe COVID-19 infection, resulting in hospitalization, in comparing the monovalent older vaccine with the newer bivalent vaccine were 25.2% and 58.7%. The respective rates of vaccine effectiveness against the combination of hospitalization or death were 24.9% and 61.8%. Estimates of efficacy were similar in comparing the Pfizer-BioNTech and Moderna bivalent booster vaccines, and the improved relative effectiveness of the bivalent vaccines was sustained in an analysis of adults at age 65 years or older.
Despite evidence to the contrary, some loud voices continue to state that the clinical sequelae of COVID-19 are no worse than those of influenza. The current study compares hospital outcomes of adults admitted with influenza infection vs infection with SARS-CoV-2 during Omicron predominance.
Study Synopsis and Perspective
COVID-19 remains deadlier than influenza in severe cases requiring hospitalization, a new study shows.
People who were hospitalized with Omicron COVID-19 infections were 54% more likely to die compared with people who were hospitalized with influenza, Swiss researchers found.
The results of the study continue to debunk an earlier belief from the start of the pandemic that influenza was the more dangerous of the 2 respiratory viruses. Researchers noted that the deadliness of COVID-19 compared with influenza persisted “despite virus evolution and improved management strategies.”
The study was published February 15 in JAMA Network Open and included 5212 patients in Switzerland hospitalized with COVID-19 or influenza. All the patients with COVID-19 were infected with the Omicron variant and were hospitalized between January 15, 2022, and March 15, 2022. Influenza data included cases from January 2018 to March 15, 2022.
Overall, 7.0% of patients with COVID-19 died compared with 4.4% of patients with influenza. Researchers noted that the death rate for hospitalized patients with COVID-19 had declined since their previous study, which was conducted during the first COVID-19 wave in the first half of 2020. At that time, the death rate of hospitalized patients with COVID-19 was 12.8%.
Since then, 98% of the Swiss population has been vaccinated. “Vaccination still plays a significant role regarding the main outcome,” the authors conclude, as a secondary analysis in this most recent study showed that unvaccinated patients with COVID-19 were twice as likely to die compared with patients with influenza.
“Our results demonstrate that COVID-19 still cannot simply be compared with influenza,” they write.
Although the death rate among patients with COVID-19 was significantly higher, there was no difference in the rate that patients with COVID-19 or influenza were admitted to the intensive care unit, which was around 8%.
A limitation of the study was that all the COVID-19 cases did not have laboratory testing to confirm the Omicron variant. However, study authors noted that Omicron accounted for at least 95% of cases during the time the patients were hospitalized. The authors stated that they were confident that their results were not biased by the potential for other variants being included in the data.
JAMA Netw Open. 2023;6(2):e2255599.
Study Highlights
Authors:
News Author: Lisa O’Mary; CME Author: Charles P. Vega, MD
Faculty and Disclosures
Released: 3/24/2023
Note: The information on the coronavirus outbreak is continually evolving. The content within this activity serves as a historical reference to the information that was available at the time of this publication. We continue to add to the collection of activities on this subject as new information becomes available. It is the policy of Medscape Education to avoid the mention of brand names or specific manufacturers in accredited educational activities. However, manufacturer names related to the approved COVID-19 vaccines are provided in this activity in an effort to promote clarity. The use of manufacturer names should not be viewed as an endorsement by Medscape of any specific product or manufacturer.
Clinical Context
The COVID-19 pandemic has shifted considerably since the advent of the Omicron variant at the end of 2021. It is clear that Omicron more effectively eludes the primary SARS-CoV-2 vaccination series compared with previous variants, which prompted the development of 2 bivalent booster vaccines designed to improve activity against Omicron. But how effective have these bivalent boosters been? A recent study by Lin and colleagues, published in the February 23, 2023, issue of the New England Journal of Medicine, addressed this issue.[1]
Researchers had access to a large cohort of more than 6 million individuals living in the US from September 1 to November 3, 2022; 17.0% of eligible patients received the bivalent booster. Booster effectiveness against severe infection peaked at 4 weeks and then waned thereafter. The rates of vaccine effectiveness against severe COVID-19 infection, resulting in hospitalization, in comparing the monovalent older vaccine with the newer bivalent vaccine were 25.2% and 58.7%. The respective rates of vaccine effectiveness against the combination of hospitalization or death were 24.9% and 61.8%. Estimates of efficacy were similar in comparing the Pfizer-BioNTech and Moderna bivalent booster vaccines, and the improved relative effectiveness of the bivalent vaccines was sustained in an analysis of adults at age 65 years or older.
Despite evidence to the contrary, some loud voices continue to state that the clinical sequelae of COVID-19 are no worse than those of influenza. The current study compares hospital outcomes of adults admitted with influenza infection vs infection with SARS-CoV-2 during Omicron predominance.
Study Synopsis and Perspective
COVID-19 remains deadlier than influenza in severe cases requiring hospitalization, a new study shows.
People who were hospitalized with Omicron COVID-19 infections were 54% more likely to die compared with people who were hospitalized with influenza, Swiss researchers found.
The results of the study continue to debunk an earlier belief from the start of the pandemic that influenza was the more dangerous of the 2 respiratory viruses. Researchers noted that the deadliness of COVID-19 compared with influenza persisted “despite virus evolution and improved management strategies.”
The study was published February 15 in JAMA Network Open and included 5212 patients in Switzerland hospitalized with COVID-19 or influenza. All the patients with COVID-19 were infected with the Omicron variant and were hospitalized between January 15, 2022, and March 15, 2022. Influenza data included cases from January 2018 to March 15, 2022.
Overall, 7.0% of patients with COVID-19 died compared with 4.4% of patients with influenza. Researchers noted that the death rate for hospitalized patients with COVID-19 had declined since their previous study, which was conducted during the first COVID-19 wave in the first half of 2020. At that time, the death rate of hospitalized patients with COVID-19 was 12.8%.
Since then, 98% of the Swiss population has been vaccinated. “Vaccination still plays a significant role regarding the main outcome,” the authors conclude, as a secondary analysis in this most recent study showed that unvaccinated patients with COVID-19 were twice as likely to die compared with patients with influenza.
“Our results demonstrate that COVID-19 still cannot simply be compared with influenza,” they write.
Although the death rate among patients with COVID-19 was significantly higher, there was no difference in the rate that patients with COVID-19 or influenza were admitted to the intensive care unit, which was around 8%.
A limitation of the study was that all the COVID-19 cases did not have laboratory testing to confirm the Omicron variant. However, study authors noted that Omicron accounted for at least 95% of cases during the time the patients were hospitalized. The authors stated that they were confident that their results were not biased by the potential for other variants being included in the data.
JAMA Netw Open. 2023;6(2):e2255599.
Study Highlights
- The study design was a retrospective cohort analysis of adults admitted with COVID-19 infection to 1 of 15 hospitals in Switzerland from January 15 to March 15, 2022. These patients were compared with patients admitted with influenza between 2018 and 2022.
- The primary outcome of the study was all-cause in-hospital mortality. The secondary outcome was admission to the intensive care unit (ICU).
- Researchers gathered data on patients’ demographic characteristics, as well as comorbid illnesses and history of vaccination against SARS-CoV-2. The study analysis was adjusted for age, sex, and type of hospital.
- 3066 adults with SARS-CoV-2 infection were compared with 2164 adults admitted with influenza. The median ages in the COVID-19 and influenza cohorts were 71 and 74 years, respectively. The cohort was fairly evenly split between men and women, but the COVID-19 cohort had a higher percentage of men; 80% of patients in both groups had significant comorbid illnesses.
- 96.2% of patients admitted with influenza had influenza A.
- 51.9% of patients admitted with SARS-CoV-2 had at least 1 previous vaccine against infection, 25.2% had received 3 doses of SARS-CoV-2 vaccine.
- 7.0% of patients with COVID-19 died during admission vs 4.4% of patients with influenza. The respective rates of ICU admission were 8.6% and 8.3%, and the duration of ICU stay was similar in the 2 groups.
- The hazard ratio (HR) for death in comparing the SARS-CoV-2 versus influenza groups was 1.93 (95% CI, 1.47-2.54). The overall HR for ICU admission was similar between the 2 groups.
- The data indicated that patients admitted with SARS-CoV-2 had a higher daily risk of either dying or being discharged from the hospital.
- In a subgroup analysis of adults admitted specifically for symptoms related to SARS-CoV-2 or influenza the HR for hospital death rose to 2.86 (95% CI, 1.64-4.97). This comparison also yielded a significant difference in the risk for ICU admission in the SARS-CoV-2 versus influenza cohorts (HR, 1.69; 95% CI, 1.09-2.62).
- In another analysis limited to adults with SARS-CoV-2 who had not received a previous SARS-CoV-2 vaccination, the HRs vs influenza for mortality and ICU admission were 2.04 (95% CI, 1.50-2.79) and 1.42 (95% CI, 1.11-1.82).
- A previous study found that the bivalent SARS-CoV-2 booster was more effective than the monovalent booster in the prevention of severe COVID-19 disease during the Omicron-predominant period. Estimates of efficacy were similar in comparing the Pfizer-BioNTech and Moderna bivalent booster vaccines, and the improved relative effectiveness of the bivalent vaccines was sustained in an analysis of adults at age 65 years or older.
- The current study finds an approximate 2-fold increase in the risk for in-hospital mortality among patients admitted with COVID-19 vs influenza. The difference in death rates was even more pronounced for patients admitted specifically for symptomatic COVID-19 vs influenza. There was no significant difference between the COVID-19 and influenza groups for ICU admission.
- Implications for the healthcare team: The healthcare team should be aware that COVID-19 appears to have a higher mortality rate among hospitalized patients compared with influenza. However, patients should continue be educated on the benefits of receiving a COVID-19 vaccine and/or booster.
