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