Vaccines are made in several different ways depending on the micro-organism which is being used and the way in which it needs to be grown. The processes also change according to the type of vaccine which is being produced - viral or bacterial, live or inactivated.

Since viruses are parasites which can only grow in living cells, viral vaccines are produced in live cell cultures. The process for many viral vaccines begins with almost laboratory scale culture and is progressively scaled up to larger and larger culture vessels. Each one of these steps takes a finite time and cannot be accelerated.

The viruses for some other viral vaccines are grown in hen's eggs. Production planning needs to take this into account when placing orders for the eggs.

Bacterial vaccines are produced in a very similar way with production being scaled up in volume over a period of time.

Following the growth phase the micro-organisms need to be further treated to produce the vaccine. This could involve inactivation or splitting into smaller units after which the active component of the vaccine is highly purified, blended with the other constituents of the vaccine to produce what is referred to as a bulk.

The preparation of the raw materials, the cultivation of the viruses or bacteria and the production of a single bulk can take anything from 4 to 9 months.

 

Once again the process varies according to the vaccine being produced but the next step is quality control. The individual bulks need to be tested for identity - did the correct organism grow or has it changed during the growth period? Is the vaccine potent enough? Is the bulk free of contamination? Does the vaccine contain the correct ingredients in the correct amounts?

If the vaccine which is being produced has more than one constituent e.g. DTP or MMR, the next stage is to blend the bulks to produce the final vaccine. Once again many of the tests described above have to be performed on the blended vaccine. All these tests can take up to three months. Only after the manufacturer is satisfied that the bulk vaccine meets the stringent criteria set by the product licence would samples of the bulk be released to the authorities so that they can perform their tests.

Therefore, just to produce a bulk lot of a vaccine can take up to a year and we still have to progress to finished product. This is the time period which applies if there are no hitches. If any of the tests have to be repeated the production time increases.

 

 

Following satisfactory quality control tests the bulks are then used to fill the appropriate containers which could be ampoules, vials or syringes.

Once again the finished product has to be tested to make sure that it conforms to the product licence. Has the potency dropped? Is it still sterile? Does the container contain the correct volume? Is it the correct pH and so on.

Once more we are talking about a process which takes 4-10 weeks.

When we are satisfied with the finished product we then send samples of the bulks and the finished product to one of several European Official Medicines Control Agencies so that they can repeat the tests and satisfy themselves that the vaccine is suitable for use in the marketplace. They take up to 2 months to do this. Only after the vaccine is released for use in the marketplace will the manufacturers pack it in the appropriate packaging and ship it to the distribution point.

Producing, testing and delivering batches from bulks can take 5 to 7 months. The total production period for a vaccine can take almost 20 months from raw ingredient to the vaccine actually being in the surgery fridge.