2005 surprised me too. LOL Except for ebola, which I think just a handful of people here in the US got, and seems like something else that escapes me, I don’t remember any type of epidemic or pandemic in the past 20 years. So I’m a bit puzzled why the PREP Act was even passed back then.
From what I can tell, the HHS Secretary has to make a declaration invoking the Act. On top of that, it looks like there have been amendments to the declaration itself (I think they just did or are about to announce the 9th one). I bet one or the other is what you’re remembering.
President Bush - bird flu scare of 2005