- Researchers from the University of Washington have compared patients hospitalized with severe coronavirus infections to severe flu patients.
- The scientists concluded that COVID-19 patients are twice as likely to die in the hospital than those with flu, further underscoring the dangers of the novel coronavirus compared to influenza.
- Flu vaccines are advised to reduce the risk of dual infection, with researchers recommending face masks and social distancing to limit the spread of COVID-19.
The novel coronavirus was compared to the flu and common colds from the early days of COVID-19. At the time, the new illness’s clinical presentation seemed to perfectly match the symptoms of the flu and the common cold. Some people died of COVID-19, but plenty of people die from influenza infections as well. As we learned more details about SARS-CoV-2, however, it became increasingly clear that the novel virus is nothing like the flu or a cold. The pathogen is more infectious and can lead to severe complications with lasting effects. Some people suffer from “long COVID” for several months after the initial infection is cleared. Several studies also showed that the death rate is much higher than the flu, which is another reason why the novel coronavirus isn’t like the flu.
Finally, there are plenty of over-the-counter drugs to treat the flu, and there are also vaccines that help prevent infections. For COVID-19, at-home therapy is limited and vaccines will not be widely available for quite a while. The drugs that have some efficacy in COVID-19 — remdesivir, dexamethasone, blood thinners, plasma transfusions, monoclonal antibodies — can only be administered in a hospital, and some of them are only given when severe complications are present. Treating the flu in hospitals is far easier and more successful, and now a new study shows exactly that: Hospitalized COVID-19 patients are twice as likely to die as people hospitalized with the flu.
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Researchers from UW Medicine studied patients with severe COVID-19 and compared them to patients infected with influenza A or B and admitted to intensive care units. The scientists looked at data from between January 1st and April 15th, publishing their findings in the Annals of the American Thoracic Society.
The researchers found that hospitalized COVID-19 patients who were critically ill had a death rate of 40%, compared to just 19% for flu patients. People infected with the novel coronavirus needed mechanical ventilation longer than flu patients. They also had worse lung function and were more likely to develop severe lung inflammation.
“The finding that ARDS (acute respiratory distress syndrome) may be more prevalent among critically ill patients with COVID is important in understanding why there may be a mortality difference between the two diseases,” lead author Dr. Natalie Cobb said, per Seattle Times. “We also found that patients with ARDS due to COVID-19 had a trend toward worse clinical outcomes than ARDS patients with influenza.”
She continued, “I strongly encourage people to get the flu vaccine and continue social-distancing measures and masking to limit the spread of COVID-19.”
The study is quite easy to go through and it’s available in full at this link. One interesting thing that the researchers explain is the signs and symptoms of the two illnesses and the results of various tests performed during hospitalization. Here’s a summary that describes the potential differences between severe coronavirus and severe influenza infections.
- COVID-19 patients had a longer symptom duration before hospitalization (7 days compared to 3.5 days)
- COVID-19 patients had more symptoms at hospital admission
- No symptoms differentiated the two diseases
- 40% of each group showed fever on admission
- White blood cell counts were higher in flu patients on admission
- Lymphocyte counts were similar, and 80% of both groups had a count lower than 1,500 per cubic mm.
- COVID-19 patients had blood inflammatory markers elevated (C-reactive protein, lactate dehydrogenase, and interleukin-6), but they were not commonly measured in flu patients
- D-dimmer was elevated in both groups, while other markers of coagulation did not differ over the first 3 days of hospitalization (INR, PTT)
- Flu patients had a higher proportion of sputum cultures that showed bacterial growth early after admission
- Staphylococcus aureus was the most common organism identified in late sputum cultures
- 15% of COVID-19 patients had positive blood cultures compared to 8% for the flu
- Viral co-infection was found in 4/36 influenza cases compared to 1/17 COVID-19 patients
- 92% of COVID-19 patients had visible lung damage on X-rays (bilateral opacities) compared to 64% of flu patients
- A similar proportion of patients required invasive mechanical ventilation (59% for COVID-19 vs. 55% for the flu) and vasopressor therapy for shock (55% vs. 49%)
- ARDS was far more common in coronavirus patients (63% vs. 26%)
As with other studies, this one needs more research as well. This might be the first such study in the US to compare the two groups of patients, but there is one limitation that’s immediately clear for the pandemic’s current state. The conclusion that twice more COVID-19 patients are at risk of dying in the hospital compared to the flu, combined with the clinical presentation detailed above, does show that the new virus is more dangerous and lethal than the flu — and that it was difficult to treat early in the pandemic. However, the COVID-19 treatment that doctors had access to at the time included only hydroxychloroquine, a drug we now know it’s not effective against COVID-19. Comparatively, influenza patients were given a known antiviral, with oseltamivir being the most common.
COVID-19 therapy has improved significantly since mid-April when this study ended. Patients will be given blood thinners, remdesivir, and dexamethasone in the hospital, depending on their condition and the availability of drugs. Blood plasma transfusions and other experimental drugs might also be available in some medical centers. These treatments could save more lives than before, and we already know that COVID-19 therapy has improved significantly. But thousands of people die of COVID-19 each day in the US right now, and flu deaths are nowhere near that high. More hospitalized COVID-19 patients will likely die than those with flu, despite access to better treatment. Also, people have been dying of coronavirus complications every day since the pandemic began. Meanwhile, the flu is mostly active during the winter.
Countries from the southern hemisphere showed that preventive measures against COVID-19 can effectively block the flu epidemics as well. That means face masks and social distancing can also help to prevent flu deaths in the northern hemisphere this year.
