Covid-19 is much more dangerous than the seasonal flu.
For starters, it's
more contagious. The average person, even with mild symptoms, is likely to spread the disease to more than two people. By contrast, the seasonal flu's rate is
roughly half.
In addition, the incubation period of the coronavirus is
2-14 days, with some suspicions that it could be even longer than that. The flu incubation period is usually 1-4 days, and in extreme cases, it can range up to five days. This means that the period in which the virus can be transmitted is around 3 times higher than influenza, which also helps to explain why it's so contagious.
In addition, there are some asymptomatic cases, but they can still spread the disease, making it very difficult to keep track of all Covid-19 cases. Add a potentially
high reinfection rate and you end up with a disease that's far more contagious and insidious than the flu.
It's not just the spread of disease, either — the other major reason why officials are so worried about Covid-19 is that it is lethal far more often than influenza. The
seasonal flu is lethal in less than
0.1% of all cases, compared to 1-2%
for COVID-19 — this makes it closer to the infamous 1918 influenza epidemic known as the "Spanish flu," which infected a quarter of a planed and had a kill
rate of about 2.5%.