Rare Flu Virus in Labs Poses 'Very Low' Risk
CDC 'Concerned' That Rare Strain Was Used in Testing Kits
April 13, 2005 -- As labs in the U.S. and around the world destroy test kits containing a rare flu virus, the CDC says the virus poses "very low risk" to the public and lab workers.
However, CDC Director Julie Gerberding, MD, MPH, says the CDC is "very concerned" that this particular virus was used for proficiency testing since the virus has been out of circulation and the public isn't immune to it.
"There is no evidence that any person has acquired H2N2," she says, referring to a strain of the influenza virus inadvertently sent to 4,000 or more labs in 18 countries, including the U.S.
According to the CDC, the H2N2 virus identified in the testing kit was found to be similar to H2N2 viruses that circulated in humans in 1957-58 at the beginning of the so-called Asian influenza pandemic. Between 1 million and 4 million people died from that outbreak.
Most of labs have already destroyed the virus, says Gerberding, who did not have exact numbers on how many kits have been destroyed. The kits were made by Meridian Bioscience Inc. and distributed by the College of American Pathologists (CAP) and other groups to test lab proficiency, says Gerberding.
"We are not taking any chances and are doing everything we can to make sure that there's no threat to human health," she says.
CDC: No Unusual Flu Cases Seen
The CDC hasn't seen any unusual flu cases this year, says Gerberding. "We are not anticipating that any is circulating because by now we would have been able to detect it," she says.
Lab staff who worked with the test kits last fall, which contained the H2N2 strain, have already cleared the potential incubation period without any cases, she said. Labs have been advised to monitor more recent kit recipients.
Virus May Not Be as Infectious
After the Asian flu epidemic, the H2N2 strain continued to cause annual epidemics until 1968 and disappeared after a new strain, H3N2, caused the next pandemic.
Anyone born after 1968 has little or no protection from the H2N2 virus, says the World Health Organization. "The population does not have immunity to this isolate, particularly our younger people," says Gerberding.