It is reasonable to expect a batch or handling error eg cold storage chain problem given the confinement of febrile illness/ febrile seizures to WA.
I've received two phones calls from the Health Department since my DD's reaction and I have asked this question. They assured me they have strict guidelines about storage. Any vaccines that were affected by the storm would be discarded. She also said, if in the very unlikely event that an "off" vaccine was used, it would be less affective rather than cause an adverse reaction.

Who knows if we'll ever be told why this has happened. It seems they avoiding admitting any of these reactions have anything to do with the vaccine. But for any parent that saw their child go through a reaction, KNOW it was the vaccine.