Aim: To survery the levels of serum anti-influenza virus antibodies and variable extent of the virus in the young people.
Methods: The levels of anti-influenza virus antibody in the serum samples collected from 3 000 young people of eight different areas in China in spring and autumn per year during 1997-2000 were detected by microhemagglutination inhibition test.
Results: The antibody levels of the young people fluctuated between the spring and autumn per year. The levels of antibody against type A3 virus (H3N2) preserved high from 1999-2000, while the level of antibody to type A1 (H1N1) decreased from 1998 to 2000 and the percentages of people susceptible to this type rose from 15% to 75%.
Conclusion: The epidemic of H3N2, H1N1 viruses and influenza virus type has occurred at some areas in China. Significant variation appeared in H1N1 virus, while the variation of H3N2 virus will be expected.