In response to the H2N2 scare, WHO sait it would develop specific biosafety recommendations on the handling of influenza A/H2N2 virus in microbiological laboratories.

However, most of the 3,747 samples that were distributed between October 2004 and February 2005 went to labs in the US.

"There are still some laboratories in the United States that haven't confirmed the destruction of the samples they were sent," said WHO spokeswoman Maria Cheng. But she added that 98% of the samples circulating in the US have been located and destroyed.

An international effort has been underway since April 12 -- when WHO first issued an alert -- to account for and destroy test kits containing the dangerous material.

New Biosafety Recommendations

The problem came to light when public health authorities in Canada and the US discovered that the College of American Pathologists (CAP), a private company in the US, had been using the H2N2 strain in its proficiency-testing panels since October 2004.

CAP contacted its client laboratories in April to request verification of the destruction of all H2N2 panels.

In response to the H2N2 scare, WHO sait it would develop specific biosafety recommendations on the handling of influenza A/H2N2 virus in microbiological laboratories.

US Samples All That Remain

Following is a list of countries that have reported completed destruction of proficiency-testing panels.