It´s impossible for Toronto to completely prepare for an inevitable large-scale outbreak of influenza, city health officials are warning.

In a report presented Tuesday to the city´s board of health, Toronto´s medical officer of health predicts that up to 914,000 people will come down with the flu during the next pandemic, and up to 12,000 of those will need to be hospitalized.

As many as 5,000 Toronto residents could die from the flu during the pandemic, the report says.

Flu pandemics sweep the globe every 35 to 40 years. Since the last such outbreak was in 1968, health officials are now working on a plan for how to deal with the inevitable illnesses and deaths that will result.

Influenza is transmitted quickly, and the sudden surge in demand for beds and health-care workers is expected to swamp hospitals and strain resources.

The city will also come under incredible strain as it tries to function with as many as a third of its workers off sick, warns the head of communicable disease control at Toronto Public Health.

"Even if you think about where you work or your children go to school, people will be off ill," said Dr. Barbara Yaffe.

"There will be issues around continuing the functioning of society [and] the delivery of essential services."

Toronto Public Health is now in the final stages of preparing its pandemic response plan.

The plan will deal with who gets flu vaccines and how health-care facilities are expanded to cope with surging numbers of patients.