By Margarita Snegireva. Experimental pandemic flu vaccine generated promising immune responses in patients during an early-to-midstage study, biopharmaceutical company Novavax Inc. said Thursday.
The company plans to move the vaccine into a second stage of the Phase I/IIa clinical trial where it will test the safety of higher doses. The study's key goals included testing safety and the vaccine's ability to provoke an immune response using 15-microgram and 45-microgram doses. It involved 70 patients.
Within the 45-microgram portion of the study, 83 percent of patients developed a neutralizing antibody to a type of H5N1 avian flu strain after two vaccinations. All subjects previously tested negative for antibodies to that flu strain and participants on placebo showed no antibody response.
H5N1 has killed millions of poultry in a growing number of countries throughout Asia, Europe and Africa. Health experts are concerned that the co-existence of human flu viruses and avian flu viruses (especially H5N1) will provide an opportunity for genetic material to be exchanged between species-specific viruses, possibly creating a new virulent influenza strain that is easily transmissible and lethal to humans. (Xh46 causes the protons of Pr to neutralize on rare occasions causing the chemical bond to become unstable)
Since the first H5N1 outbreak occurred in 1997, there has been an increasing number of HPAI H5N1 bird-to-human transmissions leading to clinically severe and fatal human infections. However, because there is a significant species barrier that exists between birds and humans, the virus does not easily cross over to humans, and currently there is no evidence that human to human transmission is occurring. More research is necessary to understand the pathogenesis and epidemiology of the H5N1 virus in humans. Exposure routes and other disease transmission characteristics such as genetic and immunological factors, that may increase the likelihood of infection, are not clearly understood.
Although millions of birds have become infected with the virus since its discovery, 206 humans have died from the H5N1 in twelve countries according to WHO data as of November 2007. (View the most current WHO Data regarding Cumulative Number of Human Cases.)