Flu vaccine update

By Dr. Ananya Mandal, MDFeb 16 2011

Faster manufacture of flu shots

Scientists have devised methods to make flu shots faster. This could mean a more reliable supply of seasonal flu vaccines and quicker responses to pandemics.

This new vaccine which could become available in the United States in the next few years, is made by growing the influenza virus in cultures of animal cells rather than in the chicken eggs that have been used for more than five decades. This shortens the process by six months. Using animal cells, which are grown in enclosed steel tanks, also reduces the risk of bacterial contamination, which has led to shortages of seasonal vaccines in some years. The study was reported in The Lancet this Tuesday.

Dr. W. Paul Glezen, an influenza expert at the Baylor College of Medicine who wrote a commentary to accompany the report, said, “I just think it’s an improvement in vaccine production that has been warranted for a long time… I just feel we’ve been sort of slow in implementing it.” He added that shorter production times would allow health officials to wait longer before deciding which strains to include in the next winter’s flu vaccine, a decision that now has to be made around February. That would increase the chance that the strains in the vaccine match the strains in circulation. Also the virus grown on chicken eggs “may not match the circulating virus as much as a vaccine made in mammalian cells,” he said.

The study involved 7,250 healthy adults and the vaccine was found to be more than 70 percent effective in preventing the seasonal flu said researchers from Baxter International, the developer of the new vaccine. That rate is similar to what egg-based vaccines have demonstrated in past studies, the researchers wrote. Side effects were similar to those of conventional vaccines, the researchers said.

The trial was sponsored by the Department of Health and Human Services which awarded $1.3 billion to six companies in 2006 to develop cell-culture flu vaccines, including $242 million to Baxter and its partner, the DynPort Vaccine Company.

This is the second vaccine trial that shows successful development on cell lines. In November, a study involving a Novartis vaccine was published in Clinical Infectious Diseases. This trial was the proof needed for regulatory approval.

P. Noel Barrett, vice president for research and development in Baxter’s bioscience division, said the company was in discussions with the FDA about what kind of data would be needed for approval. He explained that the present clinical trial included involved healthy volunteers aged 18 to 49 and compared the vaccine with a placebo. Yet children and the elderly are more vulnerable to severe problems from the flu, so for those populations it might be unethical to conduct trials using a placebo or dummy. “We are certainly committed to moving this forward into the U.S. as fast as possible,” Dr. Barrett said.

Robin Robinson, the director of the Biomedical Advanced Research and Development Authority in the Department of Health and Human Services, said cell cultures would never completely supplant egg-based production. Two of the six companies that received the federal cell-culture awards in 2006 have dropped their efforts and given back the money, he said. He added that “even faster” techniques may come up soon.

Increased risk of narcolepsy with flu vaccines

Scientists may have found why there is an increased risk for narcolepsy among some people who got the H1N1 flu vaccine. Narcolepsy causes people to suddenly fall asleep. According to the World Health Organization, excess cases of narcolepsy appear to have occurred among people with a gene that increases the risk for the rare disorder. Sweden and Finland reported the most cases, with 60 of them in the latter country. A total 12 countries reported the cases among children and adolescents who received the swine flu vaccine in 2009.

On Feb. 1, Finland’s National Institute of Health and Welfare issued the results of an analysis of all new narcolepsy cases reported between 2006 and 2010 among those born after 1990. The analysis showed an increased risk of narcolepsy among those ages 4 to 19 who received the Pandemrix H1N1 vaccine made by GlaxoSmithKline. The risk was about nine times higher for those who got the vaccine than for those of similar age who did not get vaccinated. Of 22 Finnish cases tested so far, all were carrying a gene known to increase the risk for narcolepsy, the WHO said.

The WHO said, “The National Institute considers it probable that the Pandemrix vaccine was a contributing factor to this observed increase, and has called for further investigation of other co-factors that may be associated with the increased risk…They consider it most likely that the Pandemrix vaccine increased the risk of narcolepsy in a joint effect in those genetically disposed with some other, still unknown, genetic and/or environmental factor.”