Two new flu strains have been found which have caused random spontaneous influenza infections in people living in China and Taiwan. They are subtypes from H10N8 and H6N1 influenza strains. However, a study done by The Scripps Research Institute revealed that these two strains in particular are difficult to contract.
They are avian flu viruses and have differences in how they attach to human cells. They are able to bind to host cell receptors in versatile ways, and as such can potentially mutate in distinct ways when jumping to humans. These two virus strains in particular have not acquired changes that would allow widespread transmission and a resulting pandemic. Researchers at Scripps obtained the genetic sequence from Chinese scientists and were able to produce copies of the hemagglutinin protein of the strains. They found that the receptors of bird cells bound well to the proteins, and failed to do so with human cells.
It is thought that even though there hasn't been a change in receptor specificity, sporadic cases of human infection from a bird flu virus can occur, especially if the dose of the viral exposure is high enough and it is capable of getting deep into the lungs (where there are flu-virus receptors similar to those found in birds).
Read more at: