" Professor Frazer notes there is no vaccine against the common cold, and coronaviruses are cold viruses. He says the virus enters the lungs while a vaccine enters the blood circulation to activate antibodies and white blood cells. Any proposed vaccine would not be in direct contact with the lung. Dr. Frazer goes on to say: “At the moment we don’t know how to make a coronavirus vaccine work.”
@Alex_Linder From what I've read, it seems COVID-19 causes the immune system to attack itself.