In the early stages many will disbelieve the reports of the walking dead and most nations will be caught unprepared furthermore, the state of the world after a zombie apocalypse will differ according to where the outbreak begins. For the purpose of this article it is assumed that the outbreak will begin in The Peoples Republic China.
China will be one of the worst hit in the world due to it's huge population, however it has the largest military in the world and all citizens receive at least basic military training at some point in their lives meaning that many more will be conscripted to fight. Many millions will flee during initial stages, at first by legitimate transport, then illegally as the government attempts to cap the flood of refugees and finally when all out war arrives, en masse into neighbouring countries. Despite the best efforts of the Chinese government the virus will spread abroad (their will be simply to many infected even in the early stages to be stopped). After this any connected landmass is at threat. First world countries such as The United Kingdom and the United States will receive the brunt of the refugees that will soon be made up of millions of the population of East Asia many of these will be infected. These countries will however have their own problems and will attempt to close borders. It is unlikely many will manage unless they are separated by sea and use military force to protect themselves. These nations may include Cuba and the UK. The rest of the world will have serious problems as large hordes will begin to form and surround any secured compounds.
If the United States is first hit, California would be the worst. The military forces will not get their in time and the citizens will be brutaly killed and sent off to kill the rest. Then the infection will spread through out the western states. After citizens flee the nation most of America will be lost, and by that point, the American government already fell. Leaving defenseless North America to perish. Most likley all over the world has gathered in desperate prayer and planning. In Europe and Asia, most countries have closed borders and the people begin to starve, panic, and begin to destroy their nations. In Russia, the military and police forces are not that mobilized, so many people are most likley going to escape there.
Since a lot of countries have outlawed firearm possession of the common citizens, these will quickly deteriorate, as the people living in those countries have no shooting experience prior to the outbreak. Only those with firearm knowledge, like military personnel and law enforcement officers, will stand a chance at surviving through a global catastrophe, like a zombie apocalypse, resources willing.