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Mislabeled H2N2 Virus Leads to Tighter Inventory Control Rules
April 17, 2005
>> In response to the problem, the CDC announced this week that the agency would speed up plans to require tighter security for the handling of dangerous strains of flu virus. WHO is also drafting new procedures for handling the virus, Stohr said.
But officials remained concerned that there is no comprehensive inventory of exactly how many facilities had the virus and how it was being stored. <<
The status of the inventory is the real issue behind the 1957 H2N2 shipment of mislabeled pandemic flu virus. The consensus of media reports would indicate that the strain sent out was H2N2 from an isolate from Japan. The isolate was probably the popular reference strain A/Japan/305/57(H2N2) avialable at American Type Culture Collection (ATCC VR-100). Media reports state that the shipping label indicated the strain in the unlabeled vial was H3N2 from Shanghai. The intended strain was probably one of two Shanghai isolates used to make the trivalent vaccine in the late 80's and early 90's, either A/Shanghai/11/87(H3N2) or A/Shanghai/16/89(H3N2).
In either event Meridian thought they were sending out a relatively safe H3N2 Influenza A strain, and instead sent out a pandemic H2N2 strain that evolved from the 1957 H2N2 pandemic. These H2N2 strains were replaced by H3N2 in the 1968 Hong Kong pandemic and therefore were no longer used in vaccines. Individuals born after 1968 would not have been exposed to H2N2 isolates.
The incorrectly labeled H2N2 at Meridian was one of five viruses in unlabeled vials in the kits. The proficiency kits were designed to determine if the receiving lab could correctly distinguish influenza A from influenza B. For that test, there was no difference between the two influenza A isolates, although they were different sub-types, H2N2 and H3N2. Consequently, their error went undiscovered even though many of the kits were mailed last fall.
The vials had lyophilized virus, which was highly concentrated and easily aerosolized. Proper procedures would involve opening and testing the material in a biological safety hood, designed to keep any released virus in the hood. Virus in the hood would eventually be trapped in HEPA filters and / or be killed by an antiviral agent such as bleach. Ultraviolet radiation which is emitted by an ultraviolet light in the hood, when the hood is not in use. also kills the virus.
The labs being tested would normally test the virus in safety hoods, and virus, H2N2 or H3N2, would not escape. The error was discovered because after opening the vial with H2N2 in the hood, a clinical sample was subsequently processed using the same hood. Since there was virus aerosolized in the hood, the H2N2 virus contaminated the clinical sample, since the virus in the proficiency kit was both highly concentrated and volatile. When the clinical sample was sent to the Canadian National Labs in Winnipeg for routine testing, it came back as positive for H2N2. This was a concern since H2N2 had been out of circulation since 1968. The patient was interviewed and asked about foreign travel. After a lack of evidence of a flu infection or activities that would have led to an H2N2 infection, the patient was retested and found to be negative.
The contamination was then subsequently traced back to the proficiency kit and then notifications were sent out. Since the virus was in well marked kits that were sold to the labs being tested, tracking down these kits should be relatively straight forward.
However, they key question concerns the inventory of H2N2 that is labeled H3N2. These samples will be harder to track down because exchanges are less formal, and the circumstances associated with this mislabeling need to be determined. Once this has been done, then the mislabeled virus needs to be tracked down and either destroyed or relabeled.
This tracking and inventory control will be a greater challenge than identifying and destroying the recently shipped proficiency tests. The mislabeled H2N2 could have been sent to many labs between the time it was mislabeled and now. The difficulty in tracking these samples down will be related to when the mislabeling happened, and how many labs shipped these mislabeled stocks to colleagues.
The new inventory control regulations will be designed to reduce the likelihood of future shipments of mislabeled virus. However, a situation that is potentially much more serious is the presence of another lab virus, WSN/33 in swine on farms in Korea.
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