reassortment

In addition, she said, the bird flu viruses circulating in birds and livestock “as far as we know, can’t transmit easily between people. But, if there’s reassortment, then who knows? We don’t know what kind of residual population-level immunity we would have” from a virus such as that.

But it underscored “that humans ARE susceptible to subclinical infections and possible reassortment risks, which we already knew, I guess.”

Reassortment occurs when a person or animal is infected with more than one influenza virus, allowing the two to mingle and exchange “hardware,” potentially creating a new, more virulent strain.

Another concern is something called reassortment.

Sometimes the results are benign, though it was likely a reassortment that involved an avian virus that led to the 1918 flu pandemic, which killed an estimated 50 million people.