New strains of the H5N1 virus responsible for avian flu have been found, and the virus continues to diversify. This poses a serious challenge for scientists trying to develop a vaccine against the virus. Although the diversification of avian flu is bad news, it does not mean the virus is moving closer to being able to cause a pandemic.
None of the mutations seen in the virus suggest that they increase H5N1’s ability to infect human to human. However, some scientists are questioning whether we really know enough to be able to make this assumption. They are also not suggesting the virus is more transmissible, however they are suggesting that we are not sure how that end result does develop.
The virus is breaking down into different, genetically distinct, families. This is partially caused by the spread of the virus to different countries, where they meet different pressures and change to adapt.
The Avian Flu families are called “clades”. Clade 1 virusses have circulated in Cambodia, Vietnam and Thailand. They cause human infection and have done so since 2004. Clade 2 viruses have been active in birds in Indonesia and China since 2003. The clade 2 viruses have since spread to the Middle East, Russia, Africa and Europe.
Most of the human infections since 2005 caused by H5N1 were caused by viruses included in clade 2. The WHO is recommending that scientists use this strain in their research to develop a vaccine, as this strain seems to be most active in infecting humans. Although the other strains currently being worked on should not be abandoned but by working with more strains and developing vaccines we can be more ‘prepared’ to keep up with the changing virus, especially if/when it becomes a pandemic strain.