See Success in Flu Vaccine Made by Faster Method

The 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 half a century. Using animal cells could shave weeks off the six months or so that is now required to produce a vaccine for a pandemic. In the 2009 swine flu pandemic, large quantities of vaccine were not ready until after the wave of disease appeared to have crested. 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. “I just think it’s an improvement in vaccine production that has been warranted for a long time,” said Dr. W. Paul Glezen, an influenza expert at the Baylor College of Medicine who wrote a commentary to accompany the report, which was published online Tuesday by The Lancet. “I just feel we’ve been sort of slow in implementing it.” Dr. Glezen said 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. In addition, Dr. Glezen said, when the virus grows in chicken eggs, it undergoes some changes. “It may not match the circulating virus as much as a vaccine made in mammalian cells,” he said. In a large clinical trial involving 7,250 healthy adults, the new vaccine was more than 70 percent effective in preventing the seasonal flu, according to 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. The clinical trial was paid for 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. The trial is the second to show a cell-culture influenza vaccine to be as effective as conventional ones. In November, a study involving a Novartis vaccine was published in Clinical Infectious Diseases. Experts say it is no surprise that the vaccines work. Still, proof is needed for them to win regulatory approval. Baxter began selling the vaccine in parts of Europe last October. The company, which is based in Deerfield, Ill., would not say when it would apply for approval in the United States. P. Noel Barrett, vice president for research and development in Baxter’s bioscience division, said the company was in discussions with the Food and Drug Administration about what kind of data would be needed for approval. The main issue, Dr. Barrett said, was that the clinical trial involved healthy volunteers ages 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. Baxter therefore wants to show that the vaccine produces antibodies in children and the elderly at levels that correlate with those in the adults. “We are certainly committed to moving this forward into the U.S. as fast as possible,” Dr. Barrett said. Novartis won approval for its cell-culture vaccine in Europe in 2007 and plans to start the process leading to F.D.A. approval this year. With help from a nearly $500 million federal contract, the company has built a cell-culture vaccine factory in Holly Springs, N.C. 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. Dr. Robinson said cell culture was an “interim solution” until even faster techniques come along that do not require growing the virus at all. Baxter’s flu vaccine is made in so-called Vero cells, derived from the kidneys of African green monkeys. The cells are already used to make other vaccines, including those for polio and rabies. The clinical trial was conducted in the United States during the flu season of 2008-9. Only 13 people, or 0.4 percent, of those getting the vaccine became infected with a flu virus matching one of the three strains in the vaccine, compared with 60 people, or 1.7 percent, of those getting the placebo. That translates to an effectiveness of 78.5 percent. Counting all strains of flu, even those not in the vaccine, the infection rates were 0.6 percent with the vaccine and 2.2 percent with the placebo, making the vaccine 71.5 percent effective. Side effects were similar to those of conventional vaccines, the researchers said.