No official download exists anymore. Gameloft removed Zombie Infection from the Play Store and iOS App Store around 2015 due to compatibility issues. The only way to play is via archival sites.
With the cure in hand, they made their way back to the gas station, where they administered the vaccine to the remaining survivors. As the townspeople began to recover, the group realized that their journey was far from over. The virus had spread to other towns and cities, and it would take a global effort to eradicate it. zombie infection gameloft apk obb extra quality