Types+of+Vaccines

    **Inactivated Vaccines:**  These were the first kinds of vaccines developed. These kinds of vaccines are developed are created by killing the virion (vaccine particle) using either chemicals, heat or radiation (Chaussee et al. 2011, p 3774). The then inactivated virion particles can be introduced into the body in order to trigger an immune response.

 To produce these, the virus is grown in culture or in chicken egg embryos (National institute of Allergy and Infectious Diseases website, 2011).

__Advantages of Inactivated vaccines__:
 * Easily produced
 * No chance of the virus mutating and causing infection.

__Disadvantages of Inactivated Vaccines__:


 * Stimulate a much lower immune response because as the influenza virions do not replicate in the body and 'excite' the immune system
 * Taken through intramuscular injections (needles).
 *  Because of the relatively low virulence, booster shots are often required to ensure a strong immunity is developed.

 <span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">**Live, attenuated Vaccines:** <span style="display: block; font-family: 'times new roman',times,serif; font-size: 110%;">Attenuated vaccines involve using a version of a virus which has been 'weakened' so that its virulence is decreased so that it does not cause an infection.

<span style="display: block; font-family: 'times new roman',times,serif; font-size: 110%; text-align: justify;">There are two techniques which are commonly used to create attenuated vaccines. Classical reassortment is one method, while Reverse Genetics is another. Both of these methods are designed to combine an influenza virus with a non-infectious 'donor' virus. This hybrid is much less virulent (infectious) and so can be used as a vaccine. <span style="display: block; font-family: 'times new roman',times,serif; font-size: 110%;">__Advantages of attenuated vaccines__:
 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">Classical reassortment and Reverse Genetics: **
 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">They stimulate a strong immune response, and do not need booster shots.
 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">They use intranasal delivery, instead of needle.

<span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">__Disadvantages of attenuated vaccines__:
 * <span style="display: block; font-family: 'times new roman',times,serif; font-size: 110%;">One such is that they cannot be as effectively stored at cold temperatures as inactivated vaccines, and do not have a shelf life as long as inactivated vaccines. (The World Health Organisation Website, 2011).
 * <span style="display: block; font-family: 'times new roman',times,serif; font-size: 110%;">Attenuated vaccines are still able to mutate, possibly causing severe illness.