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 Estimates vary, but based on emerging research (some of which is not yet peer-reviewed), it can take anywhere from around five to nine days after SARS-CoV-2 exposure for new coronavirus symptoms to appear.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 percent. (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 percent.
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.