Could bird flu cause a human pandemic?

Here’s what’s worrying experts right now about H5N1’s spread among dairy cows — and what isn’t.

Last year, when an H5N1 avian flu virus — commonly known as bird flu — was spilling over from bird populations into a variety of wild mammals, Seema Lakdawala, a virologist and influenza A transmission specialist at Emory University, was “not overly concerned” about human risk.