We explore the power of the antibody — a protein that our blood cells make when our body encounters a virus. Scientists have known for more than 100 years that if you take antibodies from someone who has recovered from a virus and transfer plasma, a blood byproduct, from that person to someone who is sick with that same virus, the patient will usually fare better than someone who doesn’t get this extra help. “Somebody else's army has come to help you fight the war,” said Dr. Terry Gernsheimer,