World’s largest Vaccination programme

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What is a Vaccine

A vaccine is a biological preparation that provides active acquired immunity to a particular infectious disease. A vaccine typically contains an agent that resembles a disease-causing microorganism and is often made from weakened or killed forms

What is vaccination?

• Vaccination is a simple, safe, and effective way of protecting people against harmful diseases, before they come into contact with them. It uses your body’s natural defenses to build resistance to specific infections and makes your immune system stronger.
• Vaccines train your immune system to create antibodies, just as it does when it’s exposed to a disease. 
• However, because vaccines contain only killed or weakened forms of germs like viruses or bacteria, they do not cause the disease or put you at risk of its complications.
• Most vaccines are given by an injection, but some are given orally (by mouth) or sprayed into the nose.

How does a vaccine work?

Vaccines reduce risks of getting a disease by working with your body’s natural defenses to build protection. When you get a vaccine, your immune system responds. It:

• Recognizes the invading germ, such as the virus or bacteria.
• Produces antibodies. Antibodies are proteins produced naturally by the immune system to fight disease.
• Remembers the disease and how to fight it. If you are then exposed to the germ in the future, your immune system can quickly destroy it before you become unwell.

Our immune systems are designed to remember. Once exposed to one or more doses of a vaccine, we typically remain protected against a disease for years, decades or even a lifetime. This is what makes vaccines so effective. Rather than treating a disease after it occurs, vaccines prevent us in the first instance from getting sick.

The vaccine is therefore a safe and clever way to produce an immune response in the body, without causing illness.

Different types of vaccine

There are many types of vaccines, categorized by the antigen used in their preparation. Their formulations affect how they are used, how they are stored, and how they are administered. The globally recommended vaccines discussed in this module fall into four main types.

Mono and polyvalent vaccines: 

Vaccines may be monovalent or polyvalent. A monovalent vaccine contains a single strain of a single antigen (e.g. Measles vaccine), whereas a polyvalent vaccine contains two or more strains/serotypes of the same antigen (e.g. OPV). 

Combination vaccines :

Some of the antigens above can be combined in a single injection that can prevent different diseases or that protect against multiple strains of infectious agents causing the same disease (e.g. combination vaccine DPT combining diphtheria, pertussis and tetanus antigens). Combination vaccines can be useful to overcome logistic constraints of multiple injections, and accommodate for a children’s fear of needles and pain.

Live attenuated vaccines: 

Available since the 1950s, live attenuated vaccines (LAV) are derived from disease- causing pathogens (virus or bacteria) that have been weakened under laboratory conditions. They will grow in a vaccinated individual, but because they are weak, they will cause no or very mild disease