in all likelihood the government would probably do something about it
i mean the zombie apocalypse is depicted like the government wouldn't do anything to stop it but they would
this
i'm fairly sure the national guard (or just the US Army in general) could really put down a zombie invasion quickly, especially since they have the power of aircraft
sure people are going to go batstuff insane and start killing eachother maybe but the police (in general) could just put those guys down too. Fairly sure that not a lot of people are going to go out killing everybody with AK's and full-on body armor, but again, the US Army and all those people can stop it from happening. Also, coast guard can keep any foreign ships from getting in, and airforce can keep foreign planes out. Maybe the only time a type of ship or plane could get in was if it was foreign aid and was secured rightly. Police would probably block off the main infected areas too so it won't grow larger too quickly. Oh, and don't forget handing out medicine, masks, etc.