The seasonal flu jab is being targeted at pensioners, pregnant women and those with long term health conditions, after a number of deaths linked to swine flu.
The Health Protection Agency said these groups should take up the free vaccine as it includes protection against swine flu.
It comes after three men and a woman died in the North West, the virus contributing to their deaths.
The men, two from Oldham and one from Rochdale, all had underlying health problems.
Meanwhile 32-year-old Kay Burdett, of Old Swan, died at Royal Liverpool Hospital last Friday.
She was reportedly discharged from the hospital earlier this month after spending three months there being treated for an asthma condition.
Diane Wake, Royal Liverpool Hospital’s director of nursing and operations, said: “A small number of people with flu, particularly those with chronic ill health, can become seriously ill and die.
“Most people with flu recover completely without any need to see a doctor.
“We would ask that the people of Merseyside with flu-like symptoms do not come into our emergency department, visit patients or come in for routine appointments. We are happy to rearrange appointments. This will help protect our vulnerable patients.
“The emergency department gives the same medicines you can get from a pharmacist or a GP to those people who come in with flu-like symptoms.”