Personally I will not be taking a vaccine for something that might have no physical effect on me, until at least one year of trials for side-effects have been carried out. Remember Thalidomide.
Personally I would think that the thing most effected by lack of home fans, will be the decisions made by the officials. But this would be hard to quantify, because as we know officials are not influenced by the crowd.
OK, but I must admit I am not a believer in "better than nothing". If something is sub standard, I will not watch it. That is why I will be interested to see how the German games go. I will not be watching, but I am interested in the performances.
In my view it could be a few years before a tried and tested vaccine is found ( remember Thalidomlde )
by then most people would probably be immune so would there be a big uptake of people wanting to take the vaccine. This being the case a different target for allowing spectators back would have to be found.