Vcredist (generally known as Visual C++ 2010 Redistributable) is a piece of c++ code handler, it only needs to be installed once on a host computer in order for unreal engine 4 (and 3) to work, when packaging your project you can make a installer that installs it, or request the user to install it themselves, ue4 does not do this (unless its been added to the packager but i highly doubt that)