England's Chief Medical Officer is calling on frontline health workers to get themselves vaccinated against swine flu.
Sir Liam Donaldson has urged all priority groups to take advantage of the newly-launched mass immunisation programme, which will include social care workers and those at risk.
He said: "I urge everyone in the priority groups to have the vaccine - it will help prevent people in clinical risk groups from getting swine flu and the complications that may arise from it."
Dr Peter Carter, chief executive and general secretary of the Royal College of Nursing, said the vaccine was safe and called for people to take it.
"We think it is essential that nurses and all other health workers, particularly those that come into contact with patients, should have the jab," he told Radio 5 Live.
Asked about the safety of the vaccine, he said he was "entirely satisfied" because it had undergone "rigorous testing" and claimed he was prepared to take it, adding: "This is a safe vaccine."
"It's important for them to keep well so that they are available to care for patients in the normal run of things but if the pandemic really takes off we are going to need those nurses on the wards to help to cope with the influx of those that are seriously ill."