Stan, what I think is happening is that they are taking some shortcuts because they have got loads of money (probably from the Gates Foundation).
So the Jenner are with another company, who they have worked with before. and are sort making a vaccine they have made before. So it should work
...They take a bits of the Coronovirus (identifying the right bits is the key, but there are systems and programs to do that now) and mix it an adjuvent (that is something that stimulates the immune system). The short cut I think they are doing is that they are making a very large batch before fully testing it. They are doing the testing whilst they are make 1-5 million doses of vaccine. If the vaccine does not work/is ineffective they throw it away. Thanks to the Gates money they can do it, if it was funded by government/pharm moneythey just could not afford to do it. That is how Sarah Gilbert explained it on the radio a couple of days ago. She said it would be no use, getting a working vaccine tested and approved by Christmas and then spending another 9 months making enough for immunisation. Millions will have died and the pandemic might be burnt out.
I think Sooper asked about how long the immunity lasts. That is a bit variable, and we don't quite know with THIS virus but normally if you see a certain infection (e.g. flu), or are vaccinated against it, your immune system will protect you from that strain on a second wave. Many of us have had MMR and that lasts a life time. I would imagine if a good vaccine is made...there will be pharmas all over the world ready to jump in and scale up the production