Methods: According to the principle and methods of the WHO stipulation, the influenza epidemic strains, antigen, gene variation, serum antibody and virus multi-pathogen were monitored.
方法：按who规定的原理和方法进行：对流感流行株、抗原和基因变异以及血清抗体和病毒多病原实行监测。
2
There was a significant variation in preoperative A/B-antibody titer between the centers, with a median 1:8 in Uppsala, median 1:32 in Stockholm and median 1:128 in Freiburg.