If you are arguing that geographical distance leads to inefficient supply lines, this seems dubious. Australia, third from the top, has the lowest population de

If you are arguing that geographical distance leads to inefficient supply lines, this seems dubious. Australia, third from the top, has the lowest population density of most countries listed, having a land area almost as great as the USA, but with one fifteenth of the population, and with by no means the same level of transport infrastructure. Given that the US is aiming to inoculate near 90% of the population for the current influenza problem, your deductions about distribution may need to be examined more closely.