Resolves YES if US regulators approve an H5N1 vaccine for any group of people -- for example, poultry farmers or medical workers -- or for the general population, in the absense of a pandemic.

Resolves NO if a pandemic starts and no such vaccine has been approved.

Resolves N/A at close time if neither of the above has happened.

For the purposes of this market, it's a "pandemic" if either official public health bodies call it a "pandemic", or there's eventually widespread human-to-human transmission resulting in at least 1k cases. However, the start date of the pandemic will be defined retroactively to the earliest known human-to-human transmission believed to be linked to the 1k cases. (For example, if transmission starts Feb. 1, but case numbers don't reach 1k until Mar. 1, then for the purposes of this market, the pandemic started Feb. 1.) Note that this definition is retroactive: market resolution may be delayed until we know whether "a pandemic has started" or not.