Board Thread:Show-Related Questions/@comment-68.6.118.214-20150401070511/@comment-26247132-20150407072857

The remaining 47 killed a bunch of the immune and Emerson mentions at some point in BMHB that he was the last immunized one alive (I can't remember if it was right after he returns from the Ridge/Lexa truce or when Kane, Abby, Miller, and Monroe are brought in). The MM weren't able to get their hands on any more of the 47 since Rubicon until BMHB so any marrow they injected at that point, the person would still need 48 hours before becoming immune to radiation and Clarke irradiated them sooner than that.