Bird flu H5N1 is a fast evolving virus that undergoes mutation to form more infective and highly pathogenic strains. This poses a significant challenge in the development of vaccines to protect against the virus.
Several vaccines against different strains of avian H5N1 have been developed, but continual mutation of the virus means these are now ineffective. Some of these vaccines, however, can provide cross-protection against related flu strains but the only way to provide full protection is to develop a vaccine protective against a future pandemic strain. As there is currently no pandemic, no pandemic vaccine can be developed. Only pre-pandemic vaccines can be developed, tested and refined in the hope that they will help prepare for the next pandemic. Vaccine manufacturing companies have been encouraged to expand their capacity to enable quick production of large amounts of vaccine, should a new pandemic arise.
One well-known drug that has been used to protect against H5N1 is oseltamivir, which is marketed by Roche as Tamiflu. Studies suggested that oseltamivir prevents the influenza virus spreading within the body. The drug has been stockpiled in recent years to prepare for potential bird flu pandemics. For example, in April 2006, Roche AG announced that they had three million treatment courses of Tamiflu at the disposal of the World Health Organization (WHO), ready to be used against bird flu infection. Roche also donated two million courses for WHO to use in developing nations that may be affected by a pandemic.
In 2006, however, scientists found that some strains of H5N1 were resistant to Tamiflu. Such strains have also emerged in the EU, although they remain sensitive to another drug called Relenza. Relenza is the brand name for a drug called zanamivir, which is in the same drug class as Tamiflu and has proved successful at protecting against H5N1, H9N2 and H6N1.
General precautions people can take on an individual level include the following:
- Hand washing, especially after going to the toilet and before handling food
- Covering the mouth while coughing or sneezing
- Disposing of tissues after use
- Avoiding public places if you are ill
- Ensuring a good level of general health and attending any vaccination appointments that have been recommended such as a seasonal flu jab.
- Washing the hands after any contact made with wild birds when feeding them, for example.
- Avoiding live animal markets or poultry farms if visiting an area where a bird flu outbreak has occurred.
Reviewed by Sally Robertson, BSc