When it was introduced, some people thought that it was against God's will. After all, since the human body was made in God's image, it is wrong to put something into the human body that was made from a cow. An artist of the day even drew a cartoon showing people receiving the vaccine that was made from a cow. It showed cows emerging from the leg of someone who had been vaccinated. The vaccine was smallpox vaccine, and the year was 1796.
The first smallpox vaccine worked, and still works, very nicely. It has eradicated smallpox. The weakened virus used in the vaccine is called vaccina, and it is still hard at work today.
Viruses do their damage by fooling the cell into letting it latch on. It then takes over, using its genetic information and the cell's machinery to turn out its own proteins to make more viruses. The effect on us is the disease characteristics of the infecting virus. However, vaccina is weakened, so the body's immune system can kill it without allowing the disease to develop. The body remembers that immune response and fights the disease more successfully the next time it shows up. Modern genetic engineers are adding the disease-causing genes of many viruses to the vaccina virus. In animal tests, the new vaccina virus has prevented malaria, hepatitis B. herpes simplex, rabies and other diseases.
Of course, the image of God does not refer to the physical form of the human body. Vaccines have been a great blessing, saving the lives of many so that they, too, might serve God.