We’re more concerned even than usual, because this bird flu already has developed the genetic capacity to get into a number of other mammals: seals, mink, foxes, cats and most prominently, and unexpectedly

Cats in two separate households died in May after developing severe illnesses that were confirmed as the Type A H5N1 bird virus found in U.S. dairy herds, investigators reported. Both were indoor-only cats that had no exposure to infected cattle or birds and didn’t consume raw milk.

But the study, whose publication was delayed by a pause in public communications by the agency, leaves key questions unanswered.