Profound changes in the genetic makeup of an influenza virus lead to “antigenic shift,” which results in larger changes to the structure of the virus’ surface proteins. Most people will have little to no immunity to a flu virus that has undergone an antigenic shift, and if the virus is easily spread from person-to-person, it can cause a global outbreak, called a pandemic. The most recent pandemic flu occurred in 2009 when a novel H1N1 flu virus emerged in the United States.
NIAID is continually preparing for pandemic influenza, including the potential for a wider spread of emerging strains of avian influenza, such as the H7N9 virus, which emerged in China in the spring of 2013. NIAID and its funded researchers are conducting preclinical and clinical studies on various investigational pandemic flu vaccines, including a prime-boost vaccine concept to protect against the H7N9 virus. Further human clinical trials are planned for 2017. Vaccine development to protect against other influenza subtypes, including H5, H9 and H1, is also underway.
Additionally, NIAID collaborates with BARDA and industry to evaluate vaccine “dose-sparing” strategies to maximize the supply of stockpiled flu vaccines for pandemic preparedness.
Vaccine Treatment and Evaluation Units
NIAID tests investigational flu vaccines through its longstanding Vaccine Treatment and Evaluation Units (VTEUs). Created in 1962, the VTEUs test flu vaccine candidates as well as those designed to address other diseases. The VTEUs played an essential role in the U.S. government’s rapid response to the 2009 H1N1 flu pandemic by conducting pivotal trials of an experimental vaccine. These studies determined the safety and appropriate dose of the vaccine to induce a predictably protective immune response in normal healthy adults, as well as in high-risk populations, such as children, pregnant women, the elderly and immunocompromised people. In addition, the VTEUs serve as early test sites for new, universal influenza vaccines to evaluate their safety and immunogenicity.
Scientific Advances
Single Dose of Broadly Neutralizing Antibody Protects Macaques from H5N1 Influenza
February 11, 2025A single dose of a broadly neutralizing antibody given prior to virus exposure protects macaques from severe H5N1 avian influenza, NIH scientists report.
Vaccine Protective Against H5N1 Influenza from Cattle
January 17, 2025Experimental H5N1 vaccine fully protective in mice against virus circulating in U.S. cattle.
