H5N1 bird flu virus

The concept of vaccination was developed by Pasteur in the early 19^th century. The vaccination process is composed of three parts - isolating the pathogen, inactivating it, and injecting it to the body. After the B-cells are exposed to the inactive pathogen (or even just to a part of it), they generate antibodies that specifically recognize the pathogen. Sometimes, as is the case with the H7N1 virus, injecting inactive virions will not result in specific recognition by antibodies, mainly because most of the proteins present on the virions' envelopes change rapidly. In order to make an effective vaccine, a specific protein present on the virions' envelope and bearing a stable sequence must be manually chosen and introduced to the B-cells - a process known as reverse genetics. 

The H7N1 virus strain is different from the H5N1 strain, which is more common in Asia. and for which a vaccination had already been developed. In clinical trials the new H7N1 vaccination showed little side effects and was well tolerated. The antigen presented was adjuvanted (added an aiding material) for increased immune response. According to the research team, this lethal disease can now be considered as curable. 

More information on the new vaccination can be found here.

For further discussion of the H7N1 vaccination see the TFOT forums.