I am aware of the additional cooking time required when cooking frozen meat sous-vide. Beyond that, is there additional risk in cooking meat sous-vide from frozen?
The risk should be less, compared to the same food thawed in a fridge or in room temperature, since it should spend less time in the 'danger zone' or close to it.
In general I do not think the difference is much at all, especially if you thaw in the fridge.
I believe this question was asked in the modernist cuisine forums, which I am having difficulty pulling up at this time, but I recall the answer being something to the tune of "no it is not any major risk because the surface of the meat will reach the bath temperature relatively quickly and the increase in the length of time in the bath will make up for the freezing" but i believe this may be a different story for ground meats since there is so much more surface area that will not be in contact with the bath initially due to the block it will be frozen into. I will update with links when I can access that site again.