Initiate from 2 samples, one collected from H5N1 infected patient in the South, and one taken from the embryonated chicken egg inoculated with H5N1 in the North of Viet Nam, the study group have tested the ability of PCR using the specific primers designed by the Institute of Virus of Hồng Kông and the specific primers designed by the study group to detect H5N1 in the samples.