The+Seasonal+'Flu+Shot'

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**What is the Seasonal Flu Shot?** The seasonal flu shot is the influenza vaccine which changes on an annual basis. It is one of the most important networks in the world, as it helps fight the otherwise extensive and dreadful toll influenza can take across the globe.

The seasonal influenza vaccines, is so called 'seasonal' because the virus strains it targets vary year to year.
 * This is primarily because there are several different types of influenza viruses that can affect humans.
 * Because the viruses can mutate so quickly, it can be difficult to predict which one will occur and in what part of the world will it be most common. Because of this their prevalance is monitored closely.
 * To ensure the vaccine is able to combat the rapid mutation of influenza viruses, the vaccine changes year to year.[[image:influenzavirus/World-Health-Organisation-Logo.gif align="right" caption="Figure 1: WHO logo" link="Vaccination Figure Reference#seas5"]]

The changing of the vaccine is the responsibility of numerous global health agencies, one such being the World Health Organisation (World health Organisation, Influenza vaccine, viruses and reagents, 2011).
 * WHO, among others, monitor the virus, in an attempt to predict which influenza strain will be most prevalent in the coming months.
 * These organisations then make recommendations as to what the 'make up' of the years vaccine will be (Barr et al. 2010, p 1156).

Both the inactivated and attenuated vaccines are trivalent, meaning that they contain three different influenza types.
 * This means that seasonal ‘flu shots’ are able to immunise against the three viruses which are expected to be most prevalent.

Both inactivated and the more recently approved attenuated vaccines, are both used in production of the seasonal flu shot. However, the majority of vaccines produced for influenza are inactivated.

 **Egg-based Vaccine Production:**



<span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">To ensure that the required quantity is met, a network of laboratories works through out the year to produce the vaccines. To this day the most effective vaccine production is egg-based production. In order to to create a vaccine the virus is injected into the egg and depending on the type of vaccine, (see Types of Vaccines) the virus will eventually be seperated from the egg. It may take up to six months to make a single vaccine using this process.

<span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">It takes one egg to create one vaccine.
 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">Because of this millions of eggs are needed in order to meet the international requirements.
 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">With the amount of resources required, there are currently a number of research projects underway in an attempt to find a more efficient method.