Why would there be a bigger chance of them getting myxi?
People said earlier that the current vaccine uses a dead virus, whereas the new one uses a live virus. I assume the risk may be bigger that they may contract the virus itself from the vaccine, just as there is a small risk it may happen with some human vaccines. As I said, I hope the vaccine gives better protection, however if it doesnt, and if there is a bigger risk (I guess they are going through this in the testing stage, to make it safer) then I would be happier giving my buns the 3 separate ones, especially Barney, who's immune system is likely compromised by his snuffles and anemia.
Basically I'm gonna wait and see what the benefits and dangers are of the new one, if any, before using it.