" 

 == Edit at Malaria == 

 Hi there, just wanted to clear this up. The sentence, as you are trying to re-write it, states:  I think what you are trying to say is that there is a Challenge (to create a vaccine), but that the vaccine doesn't yet exist. What the current sentence is saying is that the Challenge is the same, but the challenge itself does not exist, which is a nonsense. 

 I think the sentence as it was made perfect sense and was eloquent. I'm going to revert one last time, for the reasons I've outlined about, but if you still disagree then I will start a discussion on the talk page. I want to reiterate that I appreciate your input and am only trying to help! Regards  ⁄ "