I don't think it can be comoletely ruled out. However I do believe that's a maximun as the vaccine will be well tested and released in under a year.
The reason you need to wait so long is to prove its efficacy. By definition, you make a vaccine to give to everyone who is healthy and does not have the virus. So the absolute worst possible outcome would be to inject 95% of the population with a vaccine and discover in 6 months that it causes some horrible side effect.
This is a bizarre misunderstanding of the vaccine development process.
The catch will be if we attribute a drop off in hospital admits as successful containment or as the result of natural immunization/ herd immunity.