"A "universal influenza vaccine" could provide protection against all types of influenza and would eliminate the need to develop individual vaccines to specific H and N virus types. Such a vaccine would not need to be reengineered each year and could protect against an emergent pandemic strain. Developing a universal vaccine requires that researchers identify conserved regions of the influenza virus that do not exhibit antigenic variability by strain or over time. A universal vaccine, ACAM-FLU-A, is being developed by the British company Acambis and is being researched by others as well. Acambis (meanwhile also acquired by Sanofi Pasteur) announced in early August 2005 that it has had successful results in animal testing. The vaccine focuses on the M2 viral protein, which does not change, rather than the surface hemagglutinin and neuraminidase proteins targeted by traditional flu vaccines. The universal vaccine is made through bacterial fermentation technology, which would greatly speed up the rate of production over that possible with culture in chicken eggs, plus the vaccine could be produced constantly, since its formulation would not change. Still, such a vaccine is years away from full testing, approval, and use." As of July 2007, phase I clinical trials on humans are underway in which a vaccine that focuses on the M2 viral protein "is being administered to a small group of healthy people in order to verify the safety of the product and to provide an initial insight into the vaccine’s effect on the human immune system." (See also Universal flu vaccines) The current development state of ACAM-FLU-A is unclear.