vaccine types and mechanism

                                                vaccine 

A  vaccine is a biological preparation that provides active acquired immunity to a particular disease. The aim of a vaccine is to provoke our immune system to developed and immune response against and antigen to generate memory this process is called immunization.

The term vaccine was given by SIR EDWARD JENNER in 1796 .As he describe that the cowpox creates protective effect against small pox ,which led to the discovery of vaccines.

The term vaccine has been derived from the latin  word vaccinos meaning from cows. The aim of a  vaccine when the individul is again exposed to same antigen ,a much more stronger secondary immune response will results

In secondary response  (2nd) in short span of time  maximum number of Ig are being generate by the same antigen ,which was used during first expose. As memory cell are already present in large amount, with which antigen bind.

Types of vaccine 

1.Inactivated /killed vaccine
2.Live attenuated vaccine
3. Toxoid  vaccine
4. Sub-unit vaccine
5. DNA vaccine

1-Inactivated /killed vaccine 

Inactivated vaccine are those contain organism that have been killed or inactivated with heat or chemical. Inactivated vaccine elicit an immune response but the response often  is less complete that with attenuated vaccine.

Advantage-

1- Safer and stable 

2- easy to store and transport 

Disadvantage 

1- Stimulate weak response 

2- generally requires booster doses 

2-Live-attenuated vaccine 

This made by live organism that have been attenuated (weakened), this attenuated is done by mixing the organisms in different concentration of formaldehyde. 

Advantage- 

1-Stimulated excelled response 

2- Often confer lifelong immunity  

Disadvantage 

1- Deficiency in transportation 

2-If attenuation has not been done properly then their is chance of full blown disease within the       

 individual.