Most labs have destroyed the H2N2 influenza that was shipped worldwide

May 2005

American health officials have raised the biosafety level of A/H2N2 and are working with global health administrators to ensure that all strains of the deadly influenza virus that had been shipped to laboratories throughout the world are destroyed.

Asian influenza killed more than 1 million people in 1957, but stopped circulating in 1968 and is not included in recent vaccines. If the virus re-circulated, anyone born after 1968 would have little or no immunity to the virus.

According to Julie Gerberding, MD, director of the CDC, Meridian Bioscience Inc. in Cincinnati, the laboratory that sent the virus, most likely created test strips containing the A/H2N2 virus “not inadvertently.”

In a statement, Meridian officials said that they have a long history of supplying influenza samples to the College of American Pathologists (CAP) and they believe they were in “compliance with all applicable regulations.”

What is the risk?

CAP sent the panels out to the laboratories, as part of proficiency testing they must undergo. CDC officials said they believe CAP began shipping them out on Sept. 10, 2004. About 4,000 laboratories received the panels; most were located in the United States, Gerberding said in a recent press conference.

A Canadian laboratory had identified the A/H2N2 virus on March 26 and contacted its national health agency, which alerted WHO and the CDC to the laboratory’s findings. This set in motion an international response.

Sixty-two of the laboratories were located outside the United States and Canada, including Bermuda, Belgium, Brazil, Chile, France, Germany, Hong Kong, Israel, Italy, Japan, Lebanon, Mexico, Saudi Arabia, Singapore, South Korea, Taiwan and the United Kingdom. Gerberding said that no reports of H2N2 infection have been reported anywhere.

Sentinal labs test influenza strain samples around the country every year and unknown samples — which would include A/H2N2 — are sent to the CDC. Gerberding said no such samples have been sent to the center.

WHO officials said the proper use of biological safety cabinets and recommended personal protective equipment greatly reduces the risk of laboratory-acquired influenza.

CAP reports

All of the laboratories that received the test panels were asked to destroy those containing the A/H2N2 virus, after a request by the U.S. government. CAP further requested that destruction of the virus be confirmed and that any case of respiratory disease among the laboratory workers be investigated and reported to national authorities. WHO has a list of the addresses of the laboratories that received the panels and has contacted the ministries of health in all of the areas involved, according to Gerberding.

Gerberding said that CAP reported to them that about 99.6% of the samples have been destroyed, and WHO reported that all of the areas that were shipped the panels could account for them.

Klaus Stohr, MD, influenza chief at WHO, discussed the situation during a press conference. Several panels were originally unaccounted for in Lebanon and South Korea; however, WHO has confirmed that those panels have been found and destroyed.

WHO originally believed that a panel was also missing in Mexico, but Mexican authorities have found it. A safe destruction team traveled to Mexico City to destroy it.

The likelihood of infection is considered low when proper biosafety precautions are followed, Stohr said. The most dangerous period of transmission would have been immediately after the panels had been shipped and the laboratories were unaware of the danger.

Security implications?

A four-level system is used to describe the safety precautions needed for handling a pathogen. A/H2N2 was considered a Biosafety Level 2, which most influenza viruses are considered in the United States. According to Gerberding, the CDC and the NIH — who jointly make the decisions regarding biosafety levels — elevated A/H2N2 to a Level 3 virus, as it has been treated outside the United States.

W. Paul Glezen, MD, head epidemiologist and professor of pediatrics and molecular virology and microbiology at the Baylor College of Medicine in Houston, said Meridian Bioscience should be monitored and educated. He added that the laboratories that perform the tests use good technique to prevent accidents. Glezen said the virus should be completely sequenced so that if any human cases do occur, similarity to the laboratory strain can be checked.

According to Arnold Monto, MD, professor of epidemiology at the University of Michigan School of Public Health in Ann Arbor, viruses lose pathogenicity when shipped around the laboratory and, although the virus may still be able to infect, it could have lost the ability to cause disease among humans. Gerberding also discussed this possibility.

Monto said he believes that the Department of Homeland Security does not need to get involved. The techniques to produce even more pathogenic viruses exist, whether influenza A/H2N2 was put into the wrong hands or not, Monto said.

Monto said he believes that it is not necessary to raise the biosafety level of A/H2N2 to Level 3, although that is a “judgment call” and “debatable.” According to Monto, laboratories contain other threatening, non-influenza viruses in their freezers, and the CDC are correct to examine safety measures.

The CDC has no regulatory authority over Meridian Bioscience and other private companies.

For more information:

• Visit the WHO Web site at www.who.int.
• Visit the CDC Web site at www.cdc.gov.