A flu epidemic could sweep across Sussex this winter if not enough people get themselves vaccinated, medics have warned.
Scores of people have already been struck down by the virus with GP surgeries around the county reporting a sharp rise in patients coming in.
Cases include two strains of winter flu and swine flu.
The rise has been partly blamed on a lower than expected uptake of the annual flu vaccine so far this year.
It is believed people are refusing to take it up because this year's jab includes a vaccine for swine flu.
Concerns were raised about its safety when it was introduced last year.
NHS bosses hope news that flu cases are rising will encourage more people to come forward and get protected.
No protection means the most vulnerable people, including the over 65s and people with chronic conditions like heart disease or asthma, are potentially putting their lives at risk.
Children and pregnant women are also particularly vulnerable.
Two people are currently being treated for swine flu at the Royal Sussex County Hospital in Brighton.
Western Sussex Hospitals NHS Trust, which runs Worthing Hospital and St Richard's
Hospital in Chichester, is also dealing with a case.
Nigel Higson from the Goodwood Court Medical Centre in Road, Hove, said flu jabs were rationed to only the most vulnerable patients.
He said: “We are seeing, and have been seeing for some six weeks, an increased number of flu cases - more than I saw last winter.”
Xavier Nalletamby, from St Peter's Medical Centre, Oxford Street, Brighton, said: “We have seen a doubling of consultations this week with flu like symptoms, particularly sore throat and fever.”
NHS West Sussex immunisation lead Nick Kendall, said: “Flu is not the same as getting a cold.
“It can seriously affect your health and the risks of developing complications are far greater if you have certain pre-existing medical conditions.
"We don't know how serious flu will be this winter. But we do know that by encouraging everyone who is offered the vaccine to have it, we can make sure that those most vulnerable are protected.”