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U.S. Department of Health and Human Services

Vaccines, Blood & Biologics

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Influenza Virus Vaccine for the 1999-2000 Season

1999/2000 Season Lot Release Status (as of October 28, 1999)
Each of these manufacturers has submitted numerous lots of Influenza Virus Vaccine to CBER for lot release. The number of trivalent lots submitted by each manufacturer, along with the number of lots released by CBER, has been updated in the list below.

Manufacturer Number of Trivalent Lots Submitted with Completed Protocol Number of Lots Released by CBER
Medeva Pharma Ltd. 8 5
Parkedale Pharmaceuticals, Inc. 17 16
Connaught Laboratories, Inc. 55 55
Wyeth Laboratories, Inc. 60 60

Early each year public health experts collaborate to determine the strains of virus to be used in the manufacture of the Influenza Virus Vaccine that will be administered that fall. The recommendations are based on the data provided from laboratories worldwide as the strains are continuously evolving or mutating. Currently licensed vaccines contain three virus strains representing the strains predicted to be in U.S. circulation as recommended by the U.S. Public Health Service (FDA, CDC, NIH, and NVP) for incorporation into the vaccine for 1999-2000. These are the same strains recommended by the World Health Organization for use in the Northern Hemisphere for the same time period. Because of the necessity to have a vaccine with the virus strains currently in circulation, vaccines manufactured for the previous year can not be used. For the 1999 vaccine, the final recommendations for the three strains of influenza virus to be used in the manufacture of the 1999 vaccine were agreed upon March 11, 1999.

As soon as the strains are recommended, manufacturers begin to grow the virus strains in fertile hen's eggs. The parent strains of vaccine, known as "seed strains", used by each manufacturer are tested by FDA's Center for Biologics Evaluation and Research (CBER) to assure they are the same as the recommended strains. After the virus is harvested from the egg white, several steps are needed to purify the virus and further manufacture into monovalent concentrates. These steps are repeated for each of the three strains of the influenza virus. These monovalent concentrates may only be produced with "seed strains" pre-approved by CBER. After the purification, the trivalent vaccine is formulated using the three monovalent concentrates approved by CBER. Potency, sterility, endotoxin and other tests are conducted to assure the safety and efficacy of the vaccine. Manufacturers submit the results of their testing and sample vials from each lot to CBER for "lot release". Because of the complexity of the manufacturing process, CBER performs "lot release" on each lot of vaccine manufactured prior to distribution of the product. "Lot release" consists of CBER's review of the manufacturer's test results, including tests on the lots of monovalent virus strains and tests on the final trivalent product. Furthermore, to assure the safety and efficacy of these products, CBER performs additional testing as appropriate.

Although the manufacturing process and lot release is completed for some lots of vaccine as early as July, the manufacturing of additional lots continues until September-October. This occurs in order to manufacture and complete the testing on the almost 90 million doses expected to be used this year, an increase from approximately 20 million doses distributed in the mid-1980's.

Currently, there are four licensed manufacturers of Influenza Virus Vaccine: Medeva Pharma Ltd. manufactures Fluvirin, Parkedale Pharmaceuticals, Inc. manufactures Fluogen, Connaught Laboratories, Inc. manufactures Fluzone, and Wyeth Laboratories, Inc. manufactures Flushield.

Please be assured that CBER continues to expedite lot release of Influenza Virus Vaccine. The process of manufacturing the Influenza Virus Vaccine is a very complex one, complicated by the large number of doses administered in a very short time frame. Updated information will be provided on these products as it becomes available.