People could be putting themselves at risk by believing the flu is simply a severe cold.
Professor David Salisbury, director of immunisation for the Department of Health, warned many people would put their lives in danger by making the mistake. He also urged those at risk to visit their GP for their annual vaccination.
People over 65 are eligible for a free jab although people suffering a heart condition, chest complaints, kidney or liver disease, diabetes, people with lowered immunity or who have had a stroke are also eligible for the jab.
The figures have been released by the Department of Health to coincide with the launch of its flu vaccine campaign.
Results showed that one in three confuse the flu with a heavy cold and half believe "old wives" tales like feeding a cold and starving a fever rather than getting the jab.
Figures also reveal that one in 20 falsely believe the flu jab can give someone the flu.
Professor Salisbury said: "The research shows that common colds are frequently confused with flu, but for some, the flu virus can be potentially life-threatening.
"We are urging those at greater risk to get their flu jab from their GP."