I am just going by what I read. Attempts to create a corona virus vaccine have been in work for 20 years without success. Far more money and effort are now going into a vaccine which should help. Basically however we are just starting to test vaccine candidates to see if they actually work. Prior to this the testing has been to see if they were safe not if they were effective. When you read trials are going well it simply meant the vaccine was not killing people.
If a effective candidate emerges there are huge problems with distribution as the leading candidates require refrigeration capabilities that don’t exist on the scale needed. Initial distribution is planned and should be risk based. Normal healthy people will be far down the list. There are proposed distribution methods and a attempt to get the wealthier nations to agree to subsidize getting the vaccine to poorer nations with bad health care first. That is the right thing to do.