RIYADH, Dec 8: People intending to perform Haj this year have been cautioned against a flu pandemic. They have been advised to take an additional flu shot, since Haj is falling in winter.

“People planning to make the Haj pilgrimage should get flu shots beforehand to reduce the risk of a flu pandemic,” said doctors in the recent issue of British Medical Journal (BMJ).

Respiratory problems are already common during the Haj congregation.

Aziz Sheikh, an epidemiologist at the University of Edinburgh, has issued a warning that such a gathering makes a possibility of a global flu pandemic much more likely.

Mr Shaikh said that overcrowding was common during Haj and epidemiologists think at least one in three pilgrims would develop respiratory symptoms during the stay.

“That ratio increases when pilgrims come from economically developing nations” he said.

Such a large gathering represents a major public health risk, according to the editorial in the BMJ, particularly at a time when the risk of a pandemic is thought to be high.

"From a public health perspective, such a gathering makes the possible rampant spread of the influenza virus and a global pandemic, which many experts believe is overdue, a potentially devastating prospect that has been inadequately prepared for,” wrote Prof Aziz Sheikh and his colleagues.

The authors said the crush of people meant it was “not unusual for 50-100 people to share a tent overnight” in desert camps, a degree of overcrowding that “greatly increases the spread of respiratory infections”.

They said the World Health Organisation “must work with the Saudi authorities to minimise the risk of the influenza virus spreading among pilgrims (and the rest of us)”.