Vaccinations could reduce the cost of treating people with flu in Cumbria, health officials have said.
In the past year, NHS Cumbria spent more than £1.4m on patients who were in hospital with influenza and pneumonia.
Many of those admissions could have been avoided if people had been given a seasonal flu vaccination, officials said.
Those aged over 65, or suffering from asthma, heart disease or diabetes, have been urged to take up the free jabs.
Pregnant women are also eligible.
Dr Nigel Calvert, NHS Cumbria's associate director of public health, said: "Often people don't take flu very seriously, but for people who have an existing long term health condition as well as for older people catching flu can make people very ill and in some circumstances it can mean they end up in hospital.
"Last year around three quarters of all people aged over 65 in Cumbria had the vaccine, but only just over half of people under 65 with a long term condition did.
"We cannot be complacent, it's vital that people are aware of the risks that flu can pose and take the chance to protect themselves by having the flu jab."