A 70-year-old system could help us prepare a bird flu vaccine for humans

A 70-year-old system could help us prepare a bird flu vaccine for humans. Vaccines for influenza often make use of eggs to incubate a weakened form of the virus. The widespread presence of bird flu in US cattle and milk has vaccine scientists on high alert. Avian influenza is no newcomer in human history. In 1918, a flu pandemic ripped through war-stricken populations, resulting in the deaths of more than 50 million people – more than any other flu outbreak. Today, a highly pathogenic strain of bird flu, named H5N1, is causing concern, though human infection with this strain has so far been very rare. Since the strain's emergence in 1996, it has led to the deaths of billions of poultry birds, killed millions of birds in the wild and infected at least 700 people. In the US, a person got sick after drinking the unpasteurised milk of H5N1-infected cattle. The latest strain has not adapted to spread easily between humans. Since 2003, 700 people have been infected, with a fearsome mortality rate among humans. So far, cases of human-to-human transmission are thought to have been limited and non-sustained. But the virus's ability to jump from mammal to mammal may be changing. If the virus does gain the ability to spread efficiently in humans, a vaccine would be one way to slow its progress. According to the World Health Organization (WHO), the virus is not yet at a stage that requires a human vaccine. But in anticipation of such a change, the organisation has confirmed that there are systems and plans in place to produce one.