User blog comment:Nuclearnyancat/Eren may very well be dead/@comment-31742860-20170414224031

But if you remember Reiner was a titan shifter before Eren. He breaks the gate causing Eren and his friends to flee. Then when Eren's dad finds them he injects the serum into Eren.

From the last chapter it looks like Reiner is fine so if he is fine then Eren should be fine as well.