THE US government has declared that H7N9 bird flu "poses a significant potential for a public health emergency", and has given "emergency use authorisation" for diagnostic kits for the virus. This means tests can be used that haven't gone through the usual lengthy approval process by the US Food and Drug Administration.
They are right to be concerned. H7N9 could be a tough adversary: New Scientist has learned that it provokes a weaker immune response than most flu, making vaccines hard to produce.
Although H7N9 is not, so far, transmissible between humans, it does cause severe disease in people, is easier to catch than other bird flu strains, and may need only a few mutations to go pandemic. The UK has already given doctors instructions on when to test people for H7N9, and how to manage any with the virus.