With hospitals “rapidly” overwhelmed by patients, doctors may have to begin operating a lottery system for intensive care, the blueprint adds.
It also warns that a worst-case pandemic of “catastrophic severity” could result in the “complete or partial collapse of some or all hospital infrastructures”.
Top doctors have downplayed the predictions, saying factors such as Britain’s high state of readiness levels would lessen the impact.
The bleak forecasts come in Pandemic Influenza: Surge Capacity And Prioritisation In Health Services, a report prepared by the Department of Health last September.
It says up to half the UK population – or 30 million people – could get influenza if a bug outbreak turns into a pandemic.
The report adds: “Demand for critical care will be high and the current 3,450 adult critical care beds and 320 paediatric critical care beds in England could be rapidly overwhelmed.”