COVID-19 is an illness that infects the lungs. It is caused by a new coronavirus that started in China in late 2019 and has quickly spread worldwide.
Although it’s part of the same family of viruses that cause the common cold, the virus that causes COVID-19 is very different. Because it had never been seen in humans before, no one had existing immunity to it (that is, an ability to naturally fight it).
Unlike the flu, there is no vaccine yet to protect us. While researchers are racing to develop one, it likely won't be ready for a while.
We are learning more about the virus every day. For starters, we don’t yet know: