In recent years, the bird flu virus has caught the attention of all of Western Europe. In 2006 in particular, there was a lot of speculation about a wide-scale flu outbreak, in other words a pandemic. The Dutch government was worried about running short of vaccine, mainly because it has a very short shelf-life. All that could change, says PhD student Jean-Pierre Amorij of the University of Groningen. In his thesis he describes a way of storing flu vaccine in powder form. It can then be stored for at least a year – more than enough time to build up national stocks.
Amorij will be awarded his PhD on 4 January 2008. During the past four years he has examined all kinds of methods for long-term storage of the flu vaccine. The answer lay in what is known as freeze drying – a protein molecule, such as a vaccine, is extremely quickly frozen between millions of sugar molecules. These molecules bunch together like miniscule balls around the vaccine, so that it can be stored stably in a dried form.
Amorij did not use ordinary sugars for the freeze-drying process but special types like inulin and trehalose. It took Amorij eighteen months to find a freeze-drying process that was exactly right. That is painstaking but important work because the vaccine still has to work even after freeze drying. ‘The biggest problem was choosing the right freezing speed and the right sugar', says Amorij. But he managed it. The result looks like icing sugar.
No need for a flu jab
Freeze-dried flu vaccine not only has a longer shelf-life, it’s also easier to use. You don’t need injection needles any more as the powdered vaccine can be swallowed or inhaled. That will save a lot of time if the government has to vaccinate a lot of people very fast during a pandemic. You don’t need medical personnel to be present when swallowing or inhaling. Amorij also conducted tests on mice to see whether inhaling or swallowing worked best. ‘Inhaling was by far the most effective with the mice,’ he says. ‘The immune reaction was even more powerful than with an injection.’ According to Amorij, the powder is particularly suited to inhalation. It is very light and stays suspended so it can penetrate deep into the lungs. That makes absorption even more efficient.
When the time comes, it thus looks as if all of the Netherlands will be immunised during a pandemic via inhalers. However, according to Amorij the application will take some time yet. ‘So far we’ve only tested it on mice. The tests on people still have to take place. If everything goes well, then that could happen within five years. If there are a few setbacks it could take ten years. One thing is certain, though, it’s on its way.’
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