BETHESDA, MD. — A federal advisory panel unanimously recommended that only one of the current virus strains be changed in the production of the 2005–2006 influenza vaccine.
At last month's meeting of the Food and Drug Administration's Vaccines and Related Biological Products Advisory Committee, the decision was made to retain the influenza A (H1N1) A/New Calendonia/20/99 strain, and the influenza B/Shanghai/361/2002-like strains.
The only change recommended was to replace the influenza A (H3N2) strain with an emerging contender, one of the California-like influenza strains that were first identifed as new by the Centers for Disease Control and Prevention.
Designated A/California/7/2004, because it originated in a patient from Santa Clara County last year, the new strain proved to be one of a family of strains identified as emerging in various locations across the globe. The decision to maintain two strains and to change one in response to the emerging California-like viruses “harmonizes”—in the words of one advisory panel member—the U.S. recommendation with the identical recommendation given mere days before by the World Health Organization as to next year's vaccine mix.
Retaining last year's choices seemed appropriate for the influenza A (H1N1) and influenza B strains because there was no significant change in predominance of the strains seen in the current season, said Roland Levandowski, M.D., of the FDA's division of viral products. But there was a noticeable migration of strains of influenza A (H3N2) with the appearance of the new California strain first identified in January.
The CDC is currently trying to grow four variations of the California-like influenza virus in eggs—the first step in seeing if vaccine can be produced from the virus—with low to moderate results, said Zhiping Ye, M.D., of the FDA. Dr. Ye also noted that six national laboratories in the United States, the United Kingdom, and Japan also are working to develop A/California/7/2004-like candidates in anticipation of demand. These would be made available as candidate viruses for manufacturers to test for their suitability for bulk vaccine production.
Dr. Levandowski noted that no California-like strain had yet reached the manufacturers. But previous experience indicated that there should be no particular problem for the industry to adapt to such a recommendation in time for the next flu season, given those strains under development.
One political issue surfaced during the meeting when a number of the panelists indicated that the nearness in time of the WHO decision might make it appear that the U.S. panel was acting simply as a rubber stamp. But according to Nancy Cox, Ph.D., chief of the CDC's influenza branch, when the FDA panel meeting was held earlier than the WHO meeting, the rest of the world thought that the United States was preempting the global initiative.
Since then, the meeting has been deliberately scheduled as soon as possible after the WHO deliberations in which, according to Dr. Cox, CDC always plays a significant role. This timing, she said, was especially important because the CDC was able to return with and process the most up-to-date global information in time for presentation to the FDA panel.
Panelists and speakers alike reiterated the difficulties that manufacturers face in producing a trivalent vaccine within the short turnaround period dictated by the timing of the committee's recommendation.
A presentation by Albert Thomas, director of viral manufacturing for Sanofi Pasteur, detailed the process used by manufacturers, and emphasized how companies, seeking to accelerate the process, actually started producing the first of the monovalent strains before the committee met. That entailed an “at-risk decision” because of the economic repercussions should they prove wrong in picking which strain was the most likely to be used.
Federal authorities also are concerned about the potential spread of avian influenza. Last September, the Department of Health and Human Services awarded a contract to Aventis Pasteur to manufacture and store 2 million doses of vaccine against avian influenza A (H5N1).
The CDC has developed and distributed a test kit to detect the currently circulating H5N1 strain and is collaborating with the WHO and the National Institutes of Health on the development of additional vaccine strain candidates.
A 'B'-Deviling Problem When Caring for Children
Dealing with the B strains of the influenza virus remains a continuing problem, especially in children, according to the vaccine advisory committee.
Influenza B viruses that are currently circulating can be divided into two distinct lineages represented by B/Yamagata/16/88 and B/Victoria/2/87 (
But for the current season, Yamagata-lineage strains were predicted to predominate once more and the vaccine strain recommendation was changed to B/Shanghai/2002-like viruses, a subset of the Yamagata strains.