Kiseijuu, Ajin Recommendations
While Kiseijuu involves people who are infected by something alien and Ajin seem to be transformed humans, there's a common thread of people trying to survive in a brutal world where they don't know who they can trust.
Similar premise where the main characters are on the run with an unknown entity within them. Their normal peaceful lives come to an end and they're thrown into a kill or be killed situation. The characters are somewhat similar as well because they're in a moral dilemma and have to choose whether to support humanity or the unknown entity.
High school boy suddenly goes from Average Teen to No Longer Human and must cope with being hunted by society as well as a changing set of morals. He must find AND come to terms with his new unique place in the world - he is no longer human, but he still experiences Humanity so he doesn't quite fit with his New Kind either.
Also there's a load of blood and violence and animal instinct and emotional turmoil all under the everpresent theme of ADAPT OR DIE.
Both of the MCs have to coexist with their “invasive” counterpart. Both Ajin and Parasites are deemed inhuman. Both MCs meet more of their kind, some which happen to be extremely violent and become an adversary to the pacifist ideals of the MC. Both manga have their share of blood and gore.