The technique of vaccination was discovered in England in the late 18th century by Sir Edward Jenner, who noticed that the dangerous disease, smallpox, did riot affect milkmaids, who were exposed to a similar disease in cows, known as cowpox. Jenner used material from cow-pox sores to immunise patients against smallpox.
Vaccines are made from viruses and bacteria which have been killed or weakened by heat or chemical treatment but are still able to provoke an immune response which causes the production of antibodies to that disease. Sometimes live organisms which are non-virulent to human beings, such as cowpox, are used as vaccines.
During pregnancy most live vaccines are not permitted, since the live organisms can cross the placenta, causing abnormalities in the foetus. Smallpox, rubella, hepatitis B and yellow fever vaccines all contain live organisms, as does the Sabin vaccine against poliomyelitis. None of these are suitable for pregnant women. However the Salk vaccine against poliomyelitis and vaccines against hepatitis A and B, cholera and typhoid fever are all permissible.
The subject of vaccination is controversial. Some children have serious reactions to vaccines. However a great deal of serious disease has been prevented by vaccination. As a result of world-wide vaccinations against smallpox, the virus has become almost extinct. Among the diseases for which vaccines are available are diphtheria, tetanus, whooping cough, poliomyelitis, measles, rubella, tuberculosis, hepatitis A and B, cholera, typhoid, paratyphoid and yellow fever. Many of these vaccines are available free of charge, especially for children. It is recommended that children be vaccinated against polio at two months and begin a series of three ‘shots’ to immunise them against diphtheria, tetanus and whooping cough. Unfortunately the whooping cough vaccine can cause serious side effects in about one in 100,000 cases. In Britain, where concern about these side effects prompted many people not to have their children vaccinated, major whooping cough epidemics resulted and a number of children died or suffered serious brain damage. It would be wise to consult a doctor if you are worried about the effects of such vaccination. One should also remember that the side effects of vaccination are generally less dangerous than the disease itself.
When travelling to foreign countries where certain diseases are common, doctors often advise patients to be vaccinated a number of days before their departure to allow time for the immune system to produce the necessary antibodies.