A man is in intensive care in a Merseyside hospital with swine flu.
The man is at Southport and Formby District General Hospital but is expected to be transferred to another hospital for specialist treatment.
A spokesman for the Southport and Ormskirk NHS Trust said it had admitted a number patients since mid-October with the H1N1 virus.
Doctors have said the elderly, pregnant women and those with underlying medical conditions should have a flu jab.
Angela Kelly, deputy director of nursing at the trust, said: "It is quite common for the trust to treat patients for flu around this time of year.
"For the majority of people flu is an unpleasant illness, but in others it can be much more serious."
Dr Vin Bothra, from the Health Protection Agency in the North West, said there were some "unfounded fears" about the safety of the flu vaccine.
"While in the vast majority of people, the flu illness can be a short sharp though unpleasant illness, for some it can be very serious, leading to admissions in hospital, critical care and also death," he said.
"We have a safe and extremely effective vaccine and would urge people to use this opportunity to discuss it with their family doctor and to go and get one if they haven't already."