The National Institute of Allergy and Infectious Diseases (NIAID) is set to begin a series of clinical trials to gather data about influenza vaccines, including two candidate H1N1 flu vaccines, through a network of medical research institutions across the United States.

According to NIAID, the trials are being conducted in a compressed timeframe in an effort to beat a possible autumn resurgence of 2009 H1N1 flu infections that may occur at the same time as seasonal influenza virus strains in the Northern Hemisphere.

Information from these studies in healthy people will help officials develop recommendations for immunization schedules, including the optimal dosage and number of doses for multiple age groups, including adults, the elderly, and children. Data may also be used to support decisions about the best recommendations for people in high-risk groups, including pregnant women and people whose immune systems are weakened or otherwise compromised.

"With the emergence of the 2009 H1N1 influenza virus, we have undertaken a collaborative and efficient process of vaccine development that is proceeding in stepwise fashion," said NIAID director Anthony S. Fauci, MD, in an announcement about the clinical trials.

After the isolation and characterization of the virus, vaccine manufacturers received a 2009 H1N1 seed virus for the development of vaccine pilot lots for testing in clinical trials from the US Centers for Disease Control and Prevention (CDC).

"Now, NIAID will use our longstanding vaccine clinical trials infrastructure—the Vaccine and Treatment Evaluation Units—to help quickly evaluate these pilot lots to determine whether the vaccines are safe and to assess their ability to induce protective immune responses," said Fauci. "These data will be factored into the decision about how and if to implement a 2009 H1N1 flu immunization program this fall."

Initial studies will look at whether one or two 15 microgram doses of H1N1 vaccine are needed to induce a potentially protective immune response in healthy adult volunteers (aged 18 to 64 years old) and elderly people (aged 65 and older). Additionally, researchers will assess whether one or two 30 microgram doses are needed. The doses will be given 21 days apart, testing two manufacturers’ vaccines (Sanofi Pasteur and CSL Biotherapies). If early information from those trials indicates that these vaccines are safe, similar trials in healthy children (aged 6 months to 17 years old) will begin.

According to NIAID, a concurrent set of trials will look at the safety and immune response in healthy adult and elderly volunteers who are given the seasonal flu vaccine along with a 15 microgram dose of 2009 H1N1 vaccine. The H1N1 vaccine would be given to different sets of volunteers, either before, after, or at the same time as the seasonal flu vaccine. If early information from those studies indicates that these vaccines are safe, similar trials in healthy children (aged 6 months to 17 years old) will start.

A panel of outside experts will conduct a close review of the safety data from these trials to spot any safety concerns in real time.