At the end of the 19th century, Emil von Behring (figure 1) demonstrated that serum from horses infected with diphtheria or tetanus was useful in treating people affected by these diseases, inaugurating passive immunisation as a new therapeutic strategy. He received the Nobel Prize in Physiology or Medicine in 1901. This finding opened the door to the use of plasma from convalescent patients to treat infectious diseases; and throughout history, convalescent plasma has been used to treat many diseases, such as Spanish influenza, poliomyelitis, Korean haemorrhagic fever and, more recently, Ebola virus disease and influenza A (influenza H1N1 virus). Current evidence does not support the use of convalescent plasma in the standard therapy for COVID-19 https://bit.ly/3DGyz6t