Ministers are urging at-risk patients to get the seasonal flu jab after figures indicated that fewer people are having it than in previous years.
At the end of October, 48% of over-65s had received the jab compared with 54% at the same point in 2009, while 26% of under-65s in at-risk groups - including those with asthma, diabetes, heart disease and pregnant women - had received it, compared with 31% last year.
The Department of Health (DH) acknowledged some patients may be opting not to get the jab because of "unnecessary" fears about its swine flu component, but also conceded that the "blip" may be due to milder weather this season.
Fears about the vaccine's safety is nothing new, with many patients expressing concern about the inoculation last year too. However, the DH insists that there is nothing to worry about and people who had the swine flu vaccine last year are still covered against the strain this year, but the latest seasonal flu vaccine also protects against two other strains of flu.
Professor David Salisbury, DH Director of Immunisation, said: "We don't know how serious flu will be this winter.
"But we do know that improving seasonal flu vaccine uptake will ensure that more vulnerable people are protected.
"This year's vaccine is the ordinary seasonal flu jab and protects against the dominant strains.
"This year it protects against three types of flu, including the type known as swine flu.
"It is vital we don't underestimate the effects of this virus. It is not the same as getting a cold and it can seriously affect your health."