Exactly absolutely nothing! :-) 

Exactly !! Australians can fly to London from Europe and nearby countries board a Qantas plane and fly straight back to Perth!

Keeping the middle seat free is not the required 1.5m distance that is required. If this is what we are talking about it would mean every second row with 1 passenger per seat. There were many flights already operated with them full and no cases on board. The problem at the moment is you can lift ...