Old school shamblers are really weak so they’ll fall apart before they can leave the cemetery. They’re probably most dangerous if they just died but if there was no zombie to infect the person in the first place, you’re looking at a very controllable outbreak.
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Worst case scenario, they’re the infected kind, so you’d need to lockdown the world for a couple of days while the bodies start to decompose (that’s if the virus causes death and if the virus has permanent effects and doesn’t just eventually go away) and the local authorities start playing classic GTA with the infected. Luckily for us, we have zombies.