Besides the method of being grinded and refined into medicine, Energy Crystals could be used through the implantation method. When the Energy Crystal is implanted directly into bloodstream, your blood will be used as the carrier to transfer the energy.
In fact, this implantation method allowed people to gain strength faster with almost no energy loss.
Having said that, naturally, ordinary people would not accept the implantation of an object taken from a virus-infected body in case the object still carried the virus.
In addition to this, the Energy Crystal required blood as a carrier, which meant that it was usually implanted in the heart to get the best result. If it could not be implanted in the heart, it should at least be implanted somewhere close to the aorta. In any case, these sorts of implantation were not risk-free.
