This is a great and very relevant question! There are a few things that make coronavirus, or SARS-CoV-2, more dangerous than the flu. Firstly, coronavirus is much more contagious. Scientists measure how contagious a virus is using a statistic called R0, which indicates the expected number of people one infected person can infect. The flu has an R0 of around 0.9, while the coronavirus has an R0 of 2.63, making coronavirus nearly 3 times more contagious than the flu. The symptoms of the coronavirus can also be much worse than the flu. The death rate for seasonal influenza is 0.1%, and though the death rate for coronavirus is still being determined, experts agree that the statistic probably falls between 1-3%, making SARS-CoV-2 hundreds of times more deadly than the flu.

Why is this? Well, coronavirus makes a home in your lung tissue, which is rich in the receptors that the virus binds to. If enough of the virus is present, it can cause a condition called ARDS, or Acute Respiratory Distress Syndrome. In this case, SARS-CoV-2 releases toxic factors that can break down the boundaries in between cells in your alveoli, the air sacs in your lungs that exchange oxygen and carbon dioxide. These boundaries, known as tight junctions and adherents junctions, prevent fluid from getting into your alveoli. When coronavirus breaks apart these junctions it allows fluid to enter the alveoli, resulting in "pulmonary dead space" where gas can no longer be exchanged. This restricts the patient's ability to breathe, and is associated with a 40% death rate.

Influenza can also cause ARDS, but the factors the influenza virus releases are less efficient at breaking down cellular junctions than those released by SARS-CoV-2. Therefore, on a molecular and systemic level, coronavirus is more dangerous than the seasonal flu. Hope this helps, and thank you for your curiosity!

A lot of people would like to know exactly what makes COVID 19 (coronavirus) so dangerous. There's still a lot to learn, but here are some ideas.

First, let's talk about viruses. Viruses are not alive. They are basically DNA inside a "box" of proteins and fats. They invade our cells and turn them into virus factories.

The viruses need some way to get inside our cells. Our cells have shapes on the outside that are like antennas. They allow our cells to get messages from other cells. Viruses have shapes on their surface that fit onto receptors on the surface of our cells, tricking them into letting the virus inside. There's a nice short animation of this at: video.

Our immune systems try to protect us from invaders. When our immune system senses a cell that has "gone bad," it takes action. It sends a lot of white blood cells to the area and makes other changes. This is called the inflammation response. You can see that the word "flame" is in it. That's because an inflamed area gets hot. Blood rushes to the area, so if your skin is light, it looks red. If your skin is dark, it looks darker. It also swells up and can be painful. This can help fight the virus, but it can also cause its own problems if there's too much inflammation.

One way that COVID 19 is so dangerous is that in some people, the inflammation causes fluid to fill up the lungs. It's like drowning on dry land.

COVID 19 also seems to attack blood vessels, like veins and arteries. This causes blood clots, which can plug up the blood vessels. The plugs keep oxygen and nutrients from getting to cells, sometimes killing them. If a clot gets to the brain, it can cause a stroke.

Another reason COVID 19 is worse is because we don't have a vaccine for it yet. Vaccines are a way of warning our immune systems about specific viruses or other bad things. The flu virus changes every year, so we need new flu vaccines every year, but they do help to protect us. Some people who get the flu vaccine still get sick, but they might not get as sick.

Talk with your family about ways that you can stay safe. Remember that a lot of people who get the virus don't even feel sick. This is good in some ways. It's bad in some ways too, because a person may spread the virus without ever knowing they have it.

Short answer: it's not.

Longer answer:
Coronaviruses are a family of viruses, and some are much more dangerous than others. The same is true of flu viruses. Viruses mutate a lot, which makes them evolve quickly, and so they pick up characteristics that make them more dangerous or less dangerous. The deadliest flu in fairly recent history is the H1N1 flu of 1918 to 1919, which was worse than the current COVID coronavirus pandemic. The current COVID pandemic is worse than the flues of most years, but 1918 and 1919 were not the only years to have especially bad flues, and some of those other flues are still as bad or worse than COVID. Other coronaviruses are much less dangerous than COVID, including many that cause common colds. We still don't know exactly how bad COVID is, though; it's not as bad as the H1N1 flu, but is worse than a typical flu.

We can get a flu shot every year, which usually keeps us from getting the flu. Even if we don't get a flu shot, a lot of the people around us have gotten flu shots, so they don't get the flu, so we can be around them without getting the flu either.

There's no 'flu shot' for the coronavirus, so we can't get protected from the coronavirus with a shot. And no one around us is protected from getting the coronavirus either, so when we're around them, we might get the coronavirus. That's why scientists are working so hard to find a 'flu shot' that works for the coronavirus! And that's why we're so worried about the coronavirus, even though most people who get it will survive.

Unlike the flu, which most of us are protected from, we can get the coronavirus from anyone whose coronaviruses get into us. We don't want our hospitals overflowing with sick and dying people. [And of course we don't want to get the coronavirus ourselves!]