(RxWiki News) Current flu vaccines are seasonal, meaning new vaccines must be produced, distributed, and administered every year.
This expensive, time-consuming process could be avoided if researchers were to design a vaccine that protects recipients from the flu for decades. The production of a universal influenza vaccine is an entirely realizable goal. However, scientists from the National Institute of Allergy and Infectious Diseases (NIAID) say that licensing such a vaccine will prove difficult on a few fronts, including finding new ways to evaluate the efficacy of vaccine candidates in clinical trials.
Commenting in the journal Nature Medicine, authors Anthony S. Fauci, M.D., NIAID director, and Gary J. Nabel, M.D., Ph.D., director of the NIAID Vaccine Research Center, explain the differences between current flu vaccines and the hypothetical universal influenza vaccine. Seasonal flu vaccines must be created every year because of the changing nature of a flu protein called the hemagglutinin (HA). Both vaccination and exposure direct antibodies which attach to the head of HA. However, the head of HA changes every year, thus requiring a change of vaccine.
The making of a universal vaccine that immunizes long-term requires a detailed understanding of the flu virus's structure. Progress towards this understanding has been made. Scientists have identified a region of HA's stem that is shared across diverse flu strains. Furthermore, researchers at the NIAID Vaccine Research Center have developed a vaccine that specifically targets this shared region. The animals that received the experimental vaccine exhibited immunity to many flu virus strains.
According to Drs. Fauci and Nabel, it seems possible that one day we will have a universal flu vaccine, especially due to the growing literature on the subject. The authors also outline how such a vaccine might proceed through stages of clinical testing and licensing. They organize the known influenza subtypes into three hierarchical categories based on their likelihood of causing widespread disease in humans. The doctors recommend that developing the first batch of universal influenza vaccine candidates address the influenza virus types posing the highest threat.