28 Years Later isn't just about zombies; it is about political isolation and the fear of the "other." The film uses the quarantine of the British Isles as a metaphor for global division. The outside world has moved on, content to let the island rot, while those inside fight for scraps. It asks the question: After 30 years, are the infected the monsters, or is it the bureaucracy that left them to die?
Possible interpretations: