To get past Expert, here is the strat.
Getting the 85% immunization condition is almost impossible, because the Western states will get wrecked. Instead, build a "wall" of immunized states along the Western coast, before they get through the Southwest. Of course, remember to immunize vulnerable states around NJ and Florida as well. You should be able to contain the infection to the East Coast with good use of masks in an open government.
 "Snipe Test"){kind=icon}
 "Elephant Rave HD"){kind=icon}
 "Pandemic: American Swine"){kind=icon}
 "Move the stick around"){kind=icon}
 "The Endless Zombie Rampage"){kind=icon}