Apr 13, 2005 (CIDRAP News) The company that sent samples of the influenza virus that caused the 1957 flu pandemic to thousands of laboratories knew the identity of the virus but apparently assumed it wasn't hazardous because of its current safety classification, officials said today.
Meridian Bioscience of Cincinnati sent samples of influenza A(H2N2) to thousands of laboratories, mostly in the United States, in kits used by the labs to test their ability to identify viruses. The test kits were sent on behalf of the College of American Pathologists (CAP) and three other professional organizations.
In a teleconference this afternoon, CAP spokesman Dr. Jared Schwartz said Meridian knew what the virus was but believed it was safe. In selecting it, the company had determined that the virus was classified as a biosafety level 2 (BSL-2) agent, which meant it could legally be used in the kits, he said. Earlier reports suggested that the virus might have been mislabeled.
"We now know that they knew it was an H2N2 virus; had the college known that, we would not have allowed them to send out an H2N2, even though it's classified as biosafety level 2," Schwartz said.
He later added, "We don't know what the decision process was. It appears to have been an error in judgment in sending out an organism that had not been seen in the United States or other countries in many, many years."
But Schwartz and federal health officials said today the virus poses very little risk to lab workers and the public.
In a separate teleconference, Dr. Julie Gerberding, director of the Centers for Disease Control and Prevention (CDC), said the test kits containing the virus were sent out beginning last September. "We want to reassure the public that we have no evidence of any health threat to anyone in the community as a result of this" and no evidence of illness in lab workers, she said. "We have very good surveillance for influenza in the United States and we've not observed any unusual patterns of influenza this year. . . . If an unusual influenza virus had emerged, we'd certainly know about it by now."
The CDC notified the CAP of the situation Apr 8 and asked the organization to inform the labs and tell them to destroy the virus samples, Schwartz said. "We've asked them [the labs] to sign a piece of paper attesting that they've destroyed the virus. We've received over 1,500 of them back already," he said.
Schwartz and Gerberding said the H2N2 virus used in the kits was a reference strain, meaning it had been used in labs as a quality-control specimen for years. Gerberding said reference strains often become less virulent over time. "It's possible that this strain of virus poses a very very low risk of transmission efficiency in the public," she said. "But we have to err on the side of caution."
Gerberding said it wasn't exactly clear why Meridian picked the H2N2 virus, but commented, "It was probably a situation where the advantages of using a strain that grows well and can be easily manipulated in the lab were the driving force."
The CAP instructed Meridian to include an influenza A virus in its test kits but did not specify the type beyond that, according to Schwartz. Henceforward the college plans to give more specific instructions, he said.
Gerberding explained that for accreditation, labs generally need only to show they can determine if a virus is influenza and whether it's type A or B. "That's why we didn't learn about this earlier," she said.
The situation was discovered in March by Canada's National Microbiology Laboratory in Winnipeg, Man.
Before the problem came to light, the CDC had made a recommendation that the H2N2 virus be reclassified as a BSL-3 agent, Gerberding said. She promised to speed up the reclassification. The CDC determines the classifications in collaboration with the National Institutes of Health.
In BSL-3 labs, agents are handled with equipment designed to prevent any airborne contamination and resulting respiratory exposure, Gerberding said. Level 2 precautions are less stringent, but they can also protect workers from respiratory exposure when they are followed properly, she added.