Yes, apparently the analysis indicates that this particular virus has not mutated - still, it seems to be behaving somewhat differently. I understand that some of the victims in this cluster were young children, who would have been unlikely to be direct caregivers.

The more people get infected, the greater the chance of mutations occuring.

As I understand it, the reason H5N1 has such a high mortality rate is that it binds to sites deep in the respiratory sytem, which is also why it is not easily transmitted. Most likely a mutation that moved it higher in the tract would make it less lethal, but there is a lot of uncertainty.

Hope for the best but plan for the worst.