Scientists around the world are racing to create and test vaccines（疫苗）to help protect people against the COVID-19. They are making progress, and some vaccines have been ready.
There are many different ways to make vaccines. At least 115 different vaccines for the COVID-19 are being developed around the world right now. Many of them may not work or may have side effects that can be dangerous. That is why testing is very important.
Before a vaccine is ever tested on humans, it's first tested on animals to make sure it seems safe. Testing the vaccine on humans is done in several different periods. In Period 1, a small group of people are given small amounts of the vaccine to see if it has any bad effects.
Period 2 still tests the vaccine's safety, but it's mainly a test to see if the vaccine seems to work. If Period 2 goes well, the vaccine can begin Period 3. During Period 3, the vaccine is tried on a much larger group of people to see how well it works.
Because of the serious and worldwide influence of the COVID-19, there is huge pressure to develop a working vaccine quickly. It usually takes seven or more years to develop a safe vaccine that works well. However, Chinese scientists spent only about half a year to create working vaccines. And many people have got the vaccine so far.
