Asda is offering flu jabs to patients on a one-day only basis at a cost of £11.97.

The supermarket chain said it was undercutting the usual private charge for the injection by about £8.

Asda spokeswoman Rachel Fellows told BBC News Online: "People have responded by coming out in droves on a very wet Saturday."

In a very large number of stores people were queuing before the nurses even got there

Asda spokeswoman Rachel Fellows

Qualified nurses - employed by a private service - have been on hand in all of Asda's 250 stores.

Customers have been asked to pay for the injection at the till, fill out a form and then have the vaccination administered by a nurse.

But Ms Fellows said: "In a very large number of stores people were queuing before the nurses even got there."

A supermarket in Patchway, Bristol, even handed out boxes of chocolates and cups of tea to a queue of 100 customers, she added.

Ms Fellows said Asda would repeat the sale later in the year if customers wanted it.

'Well-worried'

Only those over 65 or with a particular risk of getting flu can have a free vaccination at their doctors.

The government is currently running a high profile campaign to urge such people to take up the jab.

Flu can cause serious complications for some

Asda is homing in on the so-called "worried well" who do not qualify but fear they may come down with flu during the winter months.

Ms Fellows said the store was targeting "people who have not had time to visit the doctor or are finding it difficult to get an appointment and want to get preventative care with their shopping".

The store is not the only retailer to offer the jabs, Boots has done so for the last three winters in selected stores.

Protecting elderly

The government is launching two initiatives to try to reduce illness and deaths among vulnerable people this winter, including a plea to the elderly and vulnerable to have a flu jab.

A second Keep Warm Keep Well campaign aims to protect older people and those with chronic conditions from the effects of the cold.

Falling temperatures in winter can contribute to the increase in deaths from respiratory disease and heart disease or strokes.

People aged 65 or over, or in a high-risk group should contact their GP for more details. Alternatively, they can call NHS Direct on 0845 4647.