Since neither of the two children, a 10-year-old boy and a 9-year-old girl, had contact with pigs, it "increases the possibility that human-to-human transmission of this new influenza virus has occurred, " according to a CDC report.

CNN: CDC: Swine flu seen in 2 California children

We shouldn't be seeing this much influenza and it's with a new virus and that's the cause fo the concern.

CNN: 2 U.S. swine flu dead had other health problems, officials say

The new virus has genes from North American swine influenza, avian influenza, human influenza and a form of swine influenza normally found in Asia and Europe, said Nancy Cox, chief of the CDC's Influenza Division.

CNN: Among the swine flu mysteries: Why only deaths in Mexico?