The H5N1 virus has been given a lot more attention than previous outbreaks of flu in birds. Scientists and science reporters are interested in it because, although other flu subtypes (H1, H7) have transmitted from birds to people, this is the first time that H5 has done so, and with a high mortality rate. In the future, H5N1 may or may not produce a strain that is transmissible between humans, but its study is likely to be significant in vaccine and virus research.
Read a backgrounder on bird flu, compiled by the independent British organisation, Sense About Science.