Patients hospitalized with Covid-19 are at greater risk of adverse outcomes including higher mortality compared to patients with influenza, according to a Spanish study presented at the European Congress of Clinical Microbiology & Infectious Diseases currently being held in Lisbon, Portugal.¹

A retrospective cohort study was conducted at a tertiary care hospital in Barcelona to assess the clinical features and the outcomes of patients hospitalized with Covid-19 vis-à-vis those hospitalized with influenza using data from the medical records. For this, the researchers recruited 187 patients with Covid-19, average age 67 years, hospitalized during the first wave of the pandemic between March 2020 and May 2020. A similar number of 187 patients with seasonal influenza, average age 76 years, hospitalized between 2017 and 2019 were also enrolled. All patients required oxygen at the time of their hospital admission.

Compared to Covid-19 patients, those with influenza had more comorbid conditions and found it difficult to carryout activities of daily life, but they were less likely to be overweight or obese.

Mortality at 30 days was the primary outcome; mortality at 3 months, length of hospital stay and treatment costs were the secondary outcomes.

The 30-day mortality due to any cause was higher in Covid-19 patients than in influenza patients; 15% (29/187) and 5% (10/187), respectively. Similarly, mortality at 3 months was 19% (35/187) in the Covid-19 group and 6% (12/187) in the influenza group. According to the authors, no differences in mortality trends were observed between the three seasonal influenza periods studied. After adjusting for variables like age, comorbidities, sex, disease severity, presence of pneumonia and steroid treatment, patients with Covid-19 were found to be at more than four times higher risk of dying within 30 days of hospital admission (hazard ratio 4.04). The HR for 90-day mortality was 3.68.

Patients with Covid-19 were likely to have severe disease and also receive intensive care (39% vs 14%, respectively). The incidence of complications like acute kidney injury was also higher in Covid patients (~22% vs 13%); moderate to severe acute respiratory distress syndrome occurred more often in Covid patients than those with influenza (46% vs 28.3%). While 9% patients suffered a pulmonary embolism, no patient in the influenza group developed this life-threatening complication. Bacterial pneumonia occurred more frequently in patients with influenza (23% vs 14.4%).

The duration of hospitalization was longer in Covid-19 patients (14 days) vs influenza patients (11 days). They were admitted to ICUs for longer period of time than influenza patients; 17 vs 10 days, respectively. The average cost of critical care of Covid patients was double that for influenza patients, €21,350 vs €12,082, respectively. Medication costs including testing costs were also higher for Covid patients.

 The findings of this study show that patients with influenza were older and they also had more underlying medical conditions. Regardless, Covid patients experienced far worse outcomes suggesting a more lethal character of SARS-CoV-2. Treatment costs incurred by Covid patients were also higher.

Prevention is always better than cure. The significance of this message has been emphatically brought home by the Covid-19 pandemic, which is showing no signs of receding. Though we are three years into the pandemic, masking, physical distancing, hand hygiene, good ventilation and avoiding crowded public places continue to be as relevant as they were before at the start of the pandemic. It is essential that all eligible persons must be fully vaccinated and boosted against Covid-19 and also be updated on their flu vaccine.

Reference

1. 01939. I. Lopez Montesinos, et al. Comparison between inpatients with COVID-19 and influenza requiring oxygen therapy in a cohort study: clinical impact and resources consumption. European Congress of Clinical Microbiology & Infectious Diseases (ECCMID 2022, Lisbon, 23-26 April. https://www.escmid.org/fileadmin/src/media/PDFs/2News_Discussions/Press_activities/2022/2020-04-21_Patients_hospitalised_with_COVID-19_.pdf