Question

Mention the four ways in which vaccines are prepared, giving the name of one disease for which each type of vaccine is used. 

Answer 1

Preparation:

1. Killed germs are introduced into the body These act as a vaccine for TAB, the vaccine for typhoid, Salk’s vaccine for poliomyelitis. Rabies vaccine for a dog bite.
2. Living weakened germs: The living germs are treated in such a way that they become very weak and as such, they cannot cause the disease. They can induce antibody formation such as the vaccine for measles and the frozen dried BCG vaccine for tuberculosis.
3. Living fully virulent germs: These virulent germs in small doses are introduced into the body as vaccine and these ArunDeep’s M-S-Biology-7 109
   produce antibodies in the body and these do not allow the germs of a particular type to cause that disease. In this vaccination, the person is inoculated with cowpox virus. It is very similar to the smallpox virus.
4. Toxoids: Toxoids are prepared from the extracts of toxins secreted by bacteria. These toxins are poisons and these are made harmless by adding formalin into them. They retain their capacity and as a result, when introduced into the body they produce antibodies into the body and do not allow the germs to grow in the body as vaccines for diphtheria and tetanus.