This photo is NOT what separating them looks like.
In order to prevent disease transmission they need to be FARRRRR apart from each other. Think far like next door far.
The sick one is shedding whatever it has and the other one has already been exposed.
Keeping them apart the way you have them it now is making ZERO difference in preventing the other from getting ill.
The other one has ALREADy been exposed and she is either going to start to show symptoms or not but I can assure that this type of separation is only stressing the birds both more which will make them sicker.