One of the greatest public health initiatives has been the introduction of immunisation. It has saved more lives than any other health promotion measures ever adopted. Immunisation was first discovered by Edward Jenner, a British scientist. The first human to be vaccinated was a boy called James Phillip, who was inoculated with cowpox virus to protect against small pox in the year 1796.
Since then vaccines have been developed for numerous infectious diseases and some diseases like small pox have been eradicated as well.
The immune system of the body is responsible for protecting against bacteria and viruses. The immune system protects by first recognising some proteins located on the coat of these organism s and recognising as non self. This is the essence of immunity-“recognition of self form non self”.
There are two sub divisions of immunity: Active and passive. Passive immunity is mediated by antibodies directed against specific proteins on the surface of the infecting organism. It is quick in onset and leads the early reaction against infection. However it does not have any memory, I.e. if challenged by the same organism again passive immunity will be of no use. So herein lays the importance of active immunity. Active immunity is mediated by the cells of immune system, especially the T lymphocytes. These cells are involved in a process of immune adaptation every time they are introduced to a foreign protein. They then produce many chemical which stimulate the production of antibodies and also call upon other cells called as natural killer (NK) cells to attack the infecting organism. The cell mediated immunity is also required for immune memory. Next time there is an infection by the same or similar organism, the T cells will stimulate production of antibodies immediately. Vaccines are actually live bacteria or viruses which have lost their disease causing potential, but still have the same proteins on their surface as the disease causing variety. Some vaccines may contain components of the coat of the organism.
The aim of immunisation is to activate the active immunity against these important causes of morbidity and death namely polio, tetanus, diphtheria, measles, whooping cough, TB, Hepatitis A, Hepatitis B, H Infulenzae, and measles.
The current recommended immunisation schedule in India is as follows.
Age Vaccine Birth
OPV zero(Oral Polio Vaccine)
Hepatitis B -1
OPV-1 + IPV-1 / OPV -1
DTPw-1 / DTPa -1(Diptheria, pertusis and tetanus)
Hepatitis B -2
Hib -1(Hemophilus Infulenzae)
OPV-2 + IPV-2 / OPV-2
DTPw-2 / DTPa -2
OPV-3 + IPV-3 / OPV -3
DTPw-3 / DTPa -3
Hepatitis B -3
9 months Measles 15-18 months
OPV-4 + IPV-B1 / OPV -4
DTPw booster -1 or DTPa booster -1
MMR -1( Mumps, measles, rubeolla)
2 years Typhoid 5 years
DTPw booster -2 or DTPa booster -2
10 years HPV(Human Papilloma Virus) Only Girls