Instead of saying "there is no evidence that Covid is airborne", they should say "there is no evidence about whether Covid is airborne or not", in other words,

Instead of saying "there is no evidence that Covid is airborne", they should say "there is no evidence about whether Covid is airborne or not", in other words, there is no evidence one way or the other. Just saying "no evidence that X" omits the crucial detail -- whether there is evidence that (not X).