I’ll admit I left my modifier dangling and further the proper work might by which instead of that. Grammar question however, it is not the subject that determine the conjugation of the verb? Since the vaccine is the subject (singular) would it not require a conjugation of the verb in the 3rd person singular. In this case saves? Were the subject pleural (vaccines for example) then it would be third person pleural conjugation (save)? If I diagram the sentence, the simple sentence is vaccine saves lives. I believe you have conjugated in your example based on the object, not the subject and it is the subject that determines the predicate.
There are not multiple vaccines against species. There is one vaccine to address the species not a distinction without difference
But you’re right — on review the sentence structure is not elegant.
Pleural. Is this a lining-of-the-lung comment?
Both nouns are, in fact, plural but Bacteria does not have an “S” on the end so the sense of a scan is that it is singular and thus “saves” follows from it. Saves, at any rate, doesn’t agree with either noun.