Some NHS staff choose not to get the flu vaccine because they wrongly believe it could make them ill, England's top nurse has said.
Professor Jane Cummings, chief nurse for England, said some "myths" persist around the vaccine, including among NHS workers, with the "big one" being that it gives people flu.
Health officials hope to achieve "near universal" coverage of frontline staff this year to help protect patients after only about two-thirds (68.7%) received the flu jab last winter.
A new analysis by Public Health England (PHE) shows the introduction of a more effective vaccine for over-65s this year could also help reduce the burden on the NHS, preventing 700 hospital deaths.
"It's really important we make it as easy as possible for staff and we give them the full facts," Prof Cummings said.
"Anything up to 50% of staff may have the flu virus but be asymptomatic, they may not feel ill, they may not be aware that they are.
"Of course, all of us as clinicians have a duty of care to our patients, so we are actually working really hard with staff this year to have the vaccine."
The flu vaccine does not contain any live viruses and cannot cause flu, though some people may experience a slight temperature and aching muscles afterwards.
Professor Cummings stressed that those turning down the vaccine because of this misconception were unlikely to be doctors and nurses.
More than 15,000 excessive deaths were attributable to flu last season, figures show.
This year, a newly-available adjuvanted vaccine will be offered to those over the age of 65, protecting against three strains of flu.
The jab could reduce GP consultations by 30,000, hospitalisations by more than 2,000 and prevent more than 700 hospital deaths from flu in England, according to analysis by PHE.
The quadrivalent vaccine, protecting against four strains, will be offered to all eligible adults under the age of 65, including pregnant women and those with long-term health conditions.
The programme has been extended this year, with children in Year Five now offered the vaccine, along with children in Reception to Year Four.
The vaccine will eventually be offered to all primary school-aged children.
Social workers and frontline healthcare workers are also eligible to receive the vaccine for free.
Professor Paul Cosford, medical director at PHE, said: "Flu is potentially a very serious illness, and we know adults over 65 are more likely to catch and have complications from flu so have the most to gain from an improved vaccine.
"By introducing an enhanced flu vaccine for this age group they will be better protected as well as helping to reduce the spread of flu to those around them.
"Further protection will be gained by offering flu vaccine to more children this year and giving a vaccine that provides protection against four strains of flu to all eligible people under the age of 65.
"We encourage everyone who is eligible to get the flu vaccine from their general practice or pharmacy before the end of November."
The flu vaccine, which will be offered to 24 million people this year, will be available from early October.
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