Thanks OYBBK: I will try and find the links later, but for now I hope you can trust a quick summary...
Although a disproportionately large number of deaths have been reported from the Ukraine, further investigation by the WHO and NIMR in the UK has determined that the virus circulating there is essentially not significantly different from strains found in other countries at various times over the last few months. In other words; thankfully there is nothing new.
The apparent higher death rate is thought to be due in part to the limited health-care facilities, and also that the average time that fatal cases took to seek medical help is between 5-6 days. So there will be people that have recovered from swine flu but not feature as mild cases in the calculation of the death rate; which then becomes disproportionately high. It is a familiar problem with early epidemiology, when you can't be sure exactly how many people have been infected, and seems a similar scenario to that in Mexico and other regions where swine flu first took off.
Sequencing analysis - performed at NIMR - of virus from several Ukraine fatal cases has shown the presence of a mutation D225G (an amino acid substitution for D (aspartic acid) to G (glycine) at position 225)), which is strongly suggested to provide a better replication in the lungs than the upper respiratory tract. However, this mutation has also been found in several other countries, including Mexico and the US many months ago, and does not seem to be enough of an evolutionary advantage for it to persist. In fact, the selection of the mutation may only occur in individual patients, and because the replication is going on deep in the lungs, is less likely to spread to others from the upper respiratory tract.