Mar 7, 2006 (CIDRAP News) – A second vaccine against human H5N1 influenza is being developed, US Health and Human Services (HHS) Secretary Mike Leavitt announced yesterday.In a speech at an immunization conference, Leavitt announced that he has authorized the National Institutes of Health (NIH) and the Centers for Disease Control and Prevention (CDC) to start work on a second vaccine, according to an Associated Press (AP) report published yesterday.The decision is routine, HHS spokesman Bill Hall told CIDRAP News today.”We’ve been following the virus and trying to monitor it. We have determined there is a strain that is distinct enough from the Asian strain that first arose,” Hall said. It was isolated in Indonesia, so it’s named after that country: A/Indonesia/5/2005.”If a third strain were to evolve, which is very likely, we would do the same thing,” he said.The United States has been testing and stockpiling vaccines based on an earlier strain of H5N1, isolated from Vietnam in 2004. Two companies, Sanofi Pasteur and Chiron Corp., have been producing the vaccines under HHS contracts worth a total of more than $200 million. But no one knows how effective those vaccines will be if the virus evolves into a pandemic strain.Work with the Indonesian strain of H5N1 began in October 2005, Ruben Donis, team leader of the molecular genetics group in the CDC’s flu branch, told Bloomberg News yesterday. He said the vaccine is ready for further development by companies now.Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases in Bethesda, Md., told the AP that this second vaccine could give pharmaceutical companies a head start if a viral variant similar to the Indonesian strain were to develop efficient human-to-human transmission.Using a CDC-developed prototype virus will allow companies to decide how best to grow viruses that can be used in the vaccine, Fauci said in the Bloomberg story. Subsequently, animal and human tests would be needed to determine the efficacy of the vaccine. Fauci said the decision to develop a second vaccine “doesn’t necessarily mean we’re going to be stockpiling doses of this vaccine.”Michael T. Osterholm, PhD, MPH, director of the University of Minnesota’s Center for Infectious Disease Research and Policy, publisher of the CIDRAP Web site, today praised HHS for closely tracking the H5N1 virus. The need to update the antigen composition shouldn’t be a surprise, he said.However, Osterholm expressed hope that eventually vaccine development will be sophisticated enough that instead of constantly updating to accommodate changes, suppliers could produce a vaccine for any H5 virus.In related developments, Sanofi Pasteur and Chiron recently reported progress in fulfilling their government contracts for producing vaccines based on older H5N1 strains. The contracts are for the national emergency stockpile of vaccines and drugs.In February, Sanofi Pasteur reported it had finished making a supply of H5N1 in bulk concentrate form under a $150 million contract with HHS. The agency originally awarded the company a $100 million contract in September 2005, and later added another $50 million for additional vaccine, the company said. The extra vaccine will be used by the US Department of Defense, the company said in a Feb 6 news release.The number of doses provided under the contract remains to be decided in clinical trials designed to determine, among other things, the optimal formulation of the vaccine, company and HHS officials have said.Sanofi recently delivered 15,000 experimental doses of the vaccine to the NIH for use in the clinical trials, the company reported in the same news release. The doses include the adjuvant aluminum hydroxide (alum), intended to stimulate the immune system so it will take less vaccine to generate an effective response. The doses contain varying amounts of antigen (active ingredient) for testing purposes.Chiron Corp. reported on Feb 24 that HHS had agreed to give the company more time to complete production of its H5N1 vaccine. HHS awarded Chiron a $62.5 million contract in October 2005 to produce the vaccine in bulk form.”Chiron is producing the vaccine at its facility in Liverpool, England, and expects to complete approximately 70 percent of the order” before switching over to production of seasonal flu vaccine in March, a company statement said. Chiron plans to switch back to producing the H5N1 vaccine this fall, after production of the seasonal vaccine is finished.