The new coronavirus is unprecedented.
By Tara C. Smith, Ph.D. –
Getty / B. Boissonnet; Designed by Morgan Johnson
If there’s one falsehood exasperating many experts who are studying and treating the new coronavirus right now, it’s “the new coronavirus is just a bad flu.” Yes, there are some similarities between the new coronavirus disease (also known as COVID-19) and the flu, namely that both are diseases caused by infectious respiratory viruses, and they have some overlapping symptoms. But there are also a number of significant differences that mean it’s not medically accurate to equate the new coronavirus and the flu. This is not a “find and replace” situation. Treating it as one underestimates a lot of what makes the new coronavirus puzzling and, as of now, much more dangerous than the flu. Here’s how the new coronavirus and the flu compare.
The most at-risk groups for COVID-19 aren’t the same as what you see with the flu.
For starters, there’s a major difference in who is most at risk of flu and new coronavirus complications.
Serious flu complications, which can include pneumonia, heart inflammation, and multisystem organ failure, typically affect children under five and people over 64 the most, according to the Centers for Disease Control and Prevention (CDC). People who have chronic medical conditions like asthma, heart disease, and diabetes are another high-risk group for flu complications, as are people who are immunocompromised due to health conditions like HIV/AIDS or medical treatments such as chemotherapy. So are pregnant people (and a fever from the flu may lead to birth defects as well).
With the new coronavirus, we do still see that those who are older (60 and over, specifically) are at higher risk of severe illness, according to the World Health Organization (WHO), as are people with certain health conditions. These include heart disease, asthma and other lung diseases, diabetes and other endocrine disorders, chronic kidney and liver diseases, and more. As with the flu, people who are immunocompromised and get the new coronavirus are at greater risk of developing a severe case. We aren’t sure if or how much pregnancy definitively increases the odds of getting the new coronavirus or experiencing related complications, but the CDC notes that pregnant people have a higher risk of severe cases of illnesses in the same family as COVID-19 (and of severe cases of respiratory infections in general).
But strangely (and very much unlike the flu), we haven’t seen many serious new coronavirus infections and deaths in children and infants. In China, the country with the most new coronavirus cases by far, a February WHO report calculated that only 2.4% of COVID-19 cases happened in children under 19, with 0.2% of those cases being critical.
We don’t even yet know the exact role that children play in spreading the SARS-CoV-2 virus that causes the new coronavirus disease, whereas we know that kids are key in spreading influenza. It’s possible that most children get mild enough cases of the new coronavirus that they don’t get tested or diagnosed but are still able to spread the disease. This is one of many new coronavirus mysteries researchers are working hard to uncover.
COVID-19 seems to be contagious longer than the flu is, and we’re still not sure about asymptomatic spreading.
Another big difference between the new coronavirus and the flu: The exact role of asymptomatic spread (transmitting the virus when you don’t have symptoms). You can spread the flu during its incubation period, which is the window of time between exposure to the virus and when you start feeling ill. That’s why people can transmit the flu to others before they realize they are sick, which is one reason it’s such a difficult disease to contain.
There is increasing evidence that this type of asymptomatic spread is happening with the new coronavirus as well. There have been several published case reports that support this idea, which is further validated by epidemiological models of the virus’s spread.
However, what’s worrying is that the new coronavirus seems to have a longer incubation period than the flu. Estimates vary, but based on emerging research (some of which is not yet peer-reviewed), it can take anywhere from around five to nine days after SARS-CoV-2 exposure for new coronavirus symptoms to appear. (Symptoms include fever, cough, and shortness of breath.) The incubation period for influenza is about two days on average, though it can span one to four days.
The long incubation period combined with the uncertainty about asymptomatic spread means that, in some ways, we’re flying blind when it comes to how best to control the transmission of the new coronavirus.
COVID-19 has a higher fatality rate than the flu, and our health systems aren’t prepared for it.
Perhaps the most significant difference between the two illnesses is that the new coronavirus currently has a higher fatality rate than the flu. On March 6, the WHO estimated that, based on the number of reported cases, the new coronavirus mortality rate was 3% to 4%. (The rate would be lower if we could take into account the number of overall cases, both reported and unreported, but many cases are going undiagnosed right now, either because of a lack of testing or because the cases are very mild. This rate also varies depending on access to quality health care). The fatality rate for the flu is generally around or below 0.1%.
Much of this comes down to the fact that the COVID-19 pandemic has largely caught the world off guard, whereas we know flu season is coming every year. We have plenty of physicians and other health care workers who have extensive experience treating influenza and know to prepare for an uptick in cases beginning each fall. We cannot say the same for COVID-19, and because of that, its ability to overwhelm health care systems is clear. We’ve seen this in Italy, which has experienced 2,158 deaths from the new coronavirus to date, and where there is a shortage of hospital beds and critical equipment.
We have flu vaccinations that, even when imperfect, reduce the number of cases, serious infections, and deaths. We also have the know-how and ability to manufacture new vaccines quickly. During the 2009 H1N1 influenza pandemic, a relatively mild pandemic compared to others in history (including the one we’re experiencing right now), the fall vaccine was delayed, but the supply had already increased by the end of the year.
No medical professionals had heard of the new coronavirus before December 2019. We have no approved vaccines, no history of making them, and no knowledge of what type of vaccine might work best. Though some clinical trials are already moving forward both for vaccine and treatment candidates, my guess is that we’re at least a year away from a vaccine (likely more), and we can’t yet know if the potential treatment options will actually be effective.
This is new for all of us. But we’re not helpless.
I know that this is so much scary information, but there’s no getting around the fact that we’re living in uncharted territory. It’s crucial that we each do our part in flattening the curve. Now is the time to try to slow the spread of the new coronavirus so we don’t overwhelm the health care system with a massive influx of cases all at one time.
Wash your hands well and often. As much as possible, avoid touching your face with unwashed hands. Practice rigorous social distancing. Read more about the steps you can take—and why this is all so important—here.
There is an adage among influenza researchers: “If you’ve seen one influenza pandemic, you’ve seen one influenza pandemic.” It’s a caution to remember that even with a familiar pathogen, not all aspects of a pandemic will be the same. This is our first coronavirus pandemic. Let’s not allow inaccurate comparisons with the flu to mislead us into complacency.
The situation with coronavirus is evolving rapidly. The advice and information in this story is accurate as of press time, but it’s possible that some data points and recommendations have changed since publication. We encourage readers to stay up to date on news and recommendations for their community by checking with their local public health department.
Tara Smith, Ph.D., is a professor of epidemiology at the Kent State University College of Public Health. She obtained her Ph.D. in microbiology at the University of Toledo and her B.S. in biology from Yale University.