Take up of the flu jab is "ridiculously low" among "vulnerable" care home workers in the Wakefield district, despite it being free of charge.
Vaccines for strains of the virus are available on the NHS for groups of people deemed particularly at risk of contracting it. This includes the over 65s, pregnant women and health workers in contact with patients.
But there is concern that care home staff are falling ill regularly because they have not been immunised.
Local health bosses are now considering ways of improving the number of people getting the vaccine, including one proposal to send people directly to care homes to administer the jab.
Speaking at a Wakefield Clinical Commissioning Group (CCG) meeting, the district's director of public health Anna Hartley said: "Most hospital staff take up the flu vaccine, but among care home staff the take up is ridiculously low.
"There's a whole lot of issues around this. Care home workers tend to be more vulnerable and they tend to be lower paid.
"There is a voucher system in place and it is free, but we're expecting care home workers to, in their spare time, go and get the flu vaccine. It's probably not realistic.
"We have to look at making the system more effective."
Ms Hartley said that there were "barriers" that needed to be broken down over vaccines generally, because of public perceptions.
She said: "The problem is a lot of people don't want immunisation.
"Often people don't think it will protect them, so we need to challenge that."