Just saw this one.
What was the population of the world at that time? 2 billion or so? So along with the 60 or so million we get another 200 million dead. I don't think those deaths would be shared equally around the world. War-torn Europe, especially Germany and Eastern Europe into Russia would be hit very hard. The lack of resources to treat such a virulent strain of the flu as well as the other diseases that may be happening would make the epidemic truly catastrophic. Japan and parts of China I think would also be hit very hard. The US might be hit hard, but given the level of organization at that time, the relative lack of destruction fromt he war, and an overall healther population than Europe at the time, will get off a bit easier than the rest of the world. For example, of the 40 million that died from the Spanish Flu at the end of WW1, only 675,00 were Americans. The number wouldn't be as low due to a much more mobile population than in the end of WW1,
Where History goes will depend upon who happens to die. If Stalin, Mao, Ho Chi Minh, Ghandi, Truman, MacArthur etc.. happen to catch the flue and die, then the late 40's and early 50's could be very different.
One of the things I can see it doing, since scientist will find out very quickly that the new anti-biotics won't work on viruses, there may be an even stronger push to find medicines and techniques to battle disease than there was in out time line.
Torqumada