“Don’t panic” over swine flu was the message today from one of America's top infectious disease specialists Dr. Kevin Cahill.

New York based Cahill, a top adviser for humanitarian affairs at the UN, said it was important for people to take "a rational approach," and follow health care advice. 

Cahill also pointed out that in the last swine flu outbreak in the U.S in 1976, more people died from taking the vaccination for the flu than the flu itself.

“We have to be very careful before we decide on mass vaccinations,” Dr. Cahill, who emphasized he was not speaking on behalf of the UN,  said. “Using masks and making sure people wash their hands in hospitals – basic principles of public health - maybe more effective.”' 

Cahill was critical in the post-9/11 anthrax investigation in New York as he was the first physician to recognize the symptoms. 

However, while Cahill stressed that people should try not to overburden the public health system, he also says that anyone who believes they have any symptoms of swine flu should see their physician immediately. 

“We are really in a very early course of an epidemic,” Cahill said. “It will take a few days before we see where this is going. There is a slight change now, however, because it appears that swine flu is now going human to human.” 

Cahill said that a lot of data on the epidemic needed to be collected. He said that health workers in hospitals faced the greater risks, and urged people to follow the advice of health professionals. “If we wait another day or two, things will become a lot clearer,” he added. 

He said the response to the SARS epidemic in 2002 and 2003 was an “over-reaction” and pointed out that it had cost Asian economies billions of dollars.