The 1.5-minute educational clip, which has been posted on YouTube and attracted more than 110,000 hits in the past two days, was broadcast during the last swine flu outbreak in the United States.

The advertisement details the ease with which the illness can infiltrate the population.

A man brings it home from the office and, by kissing his wife and children, passes the virus along.

From there it launches across the country - to the grandmother in California, to the postman, the vet and the paper boy.

"If a swine flu epidemic comes, this is how it will spread," the clip says.

"You will want to be protected, especially if you're elderly or chronically ill. Get a hit of protection. The swine flu shot."

In actual fact, the 1976 outbreak became known as the Swine Flu Fiasco after no epidemic materialised and several hundred of those immunised developed a rare form of paralysis.

The unexpected development cut short the vaccination effort after 10 weeks, and the government spent decades sorting out lawsuits.

The panic in 1976 was partly because of the belief that the 1918-19 flu pandemic, which killed half a million in the US and as many as 50 million worldwide, was caused by a swine virus.

Recent research suggests that belief was erroneous, and that the 1918-19 outbreak was an avian virus.