by Dr Pandula Siribaddana

Created on: November 10, 2009   Last Updated: November 12, 2009

What is a 'vaccine'?

'Vaccine' is a medicinal substance which will initiate an immune response in the body towards a specific disease entity either viral or bacterial. The discussion with regard to vaccine production came into light recently with the necessity to produce bulk supplies of H1N1 virus vaccines. The controversies and delays in releasing the vaccine made it necessary for the public to know an overview of the science behind the development process and the potential pitfalls which are sometimes unexpected.

How does a 'vaccine' work?

A vaccine will act as an antigen or a foreign substance which triggers the body immune cells to recognize it as a foreign body and mount a strike that would be less potent than the response towards the original virus or the bacteria which it hopes to prevent. The immune response will give rise to 'antibodies' that will remain in the body for specific number of years or even lifelong. If the original virus or the bacteria tries to invade the vaccinated person, if the immunity has been bolstered through antibodies, the body will be able to launch an immune response targeting these foreign bodies and eliminate them before causing any disease burden.

Why 'Pandemic 2009 A(H1N1)' was different?

A(H1N1) Pandemic virus also followed the path of seasonal influenza virus but it deviated from the rest in its vast and rapid expansion throughout the world as well as the wave of fatalities which it caused at the onset. The production of the virus started as early as May/June soon after the detection of the virus itself.

How's it all done?

The science involved in developing a vaccine requires the scientists to identify the disease causing virus, isolate them and grow them in a suitable culture medium and then to develop a vaccine by incorporating the produced viruses. This was done by obtaining a sample of 'Pandemic 2009 A(H1N1)' virus and mixing with seasonal influenza viruses thus making it eligible to be cultured in hens eggs. The process will give rise to a new virus which will retain certain properties of the H1N1 virus and some properties of other influenza viruses. The result will be a new virus which will have the same antigenic properties of the disease virus but less disease causing ability and that prefers the same culture media as the seasonal influenza virus.

Following development of the virus it will be made available to the vaccine manufacturers which will produce the vaccine solution using the produced viral strain or the master seed.

The H1N1 can be in two forms, one being a spray and is a live attenuated vaccine where as the other being an intra muscular injection that contains the dead virus.

What are the other methods of vaccine development?

Apart from the traditional egg based vaccine production, a new technology has been used by some manufacturers which is called 'cell based' vaccine development. The process cuts off the weeks that it takes for the virus to adopt to grow in egg based medium and fast track the vaccine production which would be ideal for pandemic situations. Apart from its fast production, it can increase its production capacity as well. The technology has been put to trial and is expected to release its first vaccine load for the general population soon.

Thus, the art and science of developing a vaccine involves many players and A(H1N1) pandemic virus gave all of them the chance to prove their metal and it's with time that we will be able to state which has survived and which has not.

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