Two groups of researchers have been working with genetically altered strains of bird flu, in an attempt to see if the virus could mutate and become more deadly to humans.

Although the H5N1 strain of bird flu had a lot of coverage in the media, it was only responsible for a few hundred human deaths worldwide. This led some scientists to say that H5N1 could never become a major worry, because it doesn’t spread easily between humans.

However, the flu virus is known for being very adaptable, so many scientists think that H5N1 could become more deadly in future.

Recent experiments have shown that, after a few generations, the virus can pass easily between ferrets. These animals are often used by flu researchers because their response to the virus is the nearest to our own.

The scientists want to publish their results as they say that they are very important for human health. However, the US National Science Advisory Board for Biosecurity (NSABB) has halted publication until they can review the evidence. Some scientists think that the danger from the virus is far greater than the benefits of the research.