Scientists rush to destroy killer flu virus

The killer "Asian" flu virus, which was sent to laboratories around the world as part of routine test kits, could trigger a pandemic if it escapes, but the chances of that are low, the World Health Organization said on Wednesday.

Senior WHO scientist Dr. Klaus Stohr said the H2N2 virus, which killed between 1 million and 4 million people in 1957, had gone to about 3,700 laboratories, nearly all in the United States.

"The virus could cause a global (flu) outbreak. It was an unwise decision to send it out," said Stohr, who heads the United Nations health agency's influenza program.

But the laboratories, which are sent viruses to test their ability to detect strains, are experienced in handling such material and most had already been alerted to the danger, so there was little chance of anyone catching it, he added.

"It is a risk, but it is considered low. It should not lead to a big scare," Stohr told Reuters.

The U.S. organisation that sent out the virus, the College of American Pathologists (CAP), has issued instructions for all samples to be destroyed and would report to the WHO and U.S. health authorities by Friday on the response, he said.

"By Friday we may be through with this," Stohr said.

Test kits sent to labs so they can check their detection proficiency normally involve viruses that are in circulation among the world's population. It was not immediately clear why the U.S. concern had opted to take a lethal strain out of cold storage.

NO IMMUNITY

The problem with the 1957 H2N2 virus was that nobody born after 1968 would have much immunity to it.

The virus, whose appearance nearly 40 years ago coincided with the so-called Asian influenza pandemic, is spread easily between humans. It continued to cause annual epidemics for a decade, when it vanished with the emergence of a new virus. As a result, it was no longer considered necessary to include it in vaccines.

But Stohr said that the laboratory scare was a one-off because there were no other such lethal flu viruses being preserved by medical institutions.

The strain that may have killed up to 40 million people in 1918 - the so-called Spanish flu - had long since disappeared and the virus of the last great influenza epidemic of 1968 was still in circulation, meaning that people had natural resistance.

PUBLIC ANNOUNCEMENT DELAYED

The United Nations health agency was first alerted on March 26 by the Canadian Public Health Agency to the fact that the H2N2 virus had been detected.

It was found because there had been cross-contamination with other flu samples in a Canadian laboratory, but the source was only identified as being the proficiency kit last Friday.