Doctor Who Rewatch -> 1x09 The Empty Child

When that bomb dropped, there was just one. Dead? At first. His injuries were truly dreadful. By the following morning, every doctor and nurse who had treated him, who had touched him, had those exact same injuries. By the morning after that, every patient in the same ward, the exact same injuries. Within a week, the entire hospital. Physical injuries as plague. Can you explain that?

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