looking at novel technologies for vaccine production that could provide better "real-time" access and be produced more affordably, thereby increasing access for people living in low- and moderate-income countries, where an influenza pandemic may likely originate, such as live attenuated (egg-based or cell-based) technology and recombinant technologies (proteins and virus-like particles). , more than seventy known clinical trials have been completed or are ongoing for pandemic influenza vaccines. In September 2009, the FDA approved four vaccines against the 2009 H1N1 influenza virus (the 2009 pandemic strain), and expected the initial vaccine lots to be available within the following month. In January 2020, the US Food and Drug Administration (FDA) approved Audenz as a vaccine for the H5N1 flu virus. Audenz is a vaccine indicated for active immunization for the prevention of disease caused by the influenza A virus H5N1 subtype contained in the vaccine. Audenz is approved for use in persons six months of age and older at increased risk of exposure to the influenza A virus H5N1 subtype contained in the vaccine. Universal flu vaccines A universal influenza vaccine that would not have to be designed and made for each flu season in each hemisphere would stabilize the supply, avoid error in predicting the season's variants, and protect against escape of the circulating strains by mutation. Such a vaccine has been the subject of research for decades. One approach is to use broadly neutralizing antibodies that, unlike the annual seasonal vaccines used over the first decades of the 21st century that provoke the body to generate an immune response, instead provide a component of the immune response itself. The first neutralizing antibodies were identified in 1993, via experimentation. It was found that the flu neutralizing antibodies bound to the stalk of the Hemagglutinin protein. Antibodies that could bind to the head of those proteins were identified. The highly conserved M2 proton channel was proposed as a potential target for broadly neutralizing antibodies. The challenges for researchers are to identify single antibodies that could neutralize many subtypes of the virus, so that they could be useful in any season, and that target conserved domains that are resistant to antigenic drift. Another approach is to take the conserved domains identified from these projects, and to deliver groups of these antigens to provoke an immune response; various approaches with different antigens, presented different ways (as fusion proteins, mounted on virus-like particles, on