| Objects:To learn the level of the Cross-Reactive Antibody to the 2009 Pandemic H1N1 Influenza Virus of ordinary people in Shanxi Province through Serological survey, aiming at analyzing the cohort immunity to the 2009 Pandemic H1N1 Influenza Virus in Shanxi Province as well as providing scientific evidence for the assessment of the spreading model and prevailing potential of the 2009 Pandemic H1N1 Influenza; to provide reference in order to preliminarily find out the duration and immune persistence of H1N1 antibody in human body and work out the vaccination (vaccinating) strategy by comparing the changing levels of antibody in people's serum at different points of time; to offer scientific basis to determine the focus group of vaccination as well as formulating and regulating strategies for the H1N1 influenza prevention and control.METHODS:Conducted five surveys successively on December 5th and 20th in 2009, and January 20th, February 20th and March 20th in 2010 at selected places including a comprehensive medical institution (Shanxi Provincial People's Hospital), and an outpatient laboratory of another comprehensive medical institution (Shanxi Provincial Children's Hospital) and a blood bank (Blood Donation House of Taiyuan Blood Testing Center); collected altogether 2100 serum samples from healthy people and non-H1N1 infected treated patents; detected the level antibody to H1N1 virus in the collected samples using the hemagglutination-inhibition assay; calculated positive rates and the average antibody titers according to different age groups, sexes and time points.RESULTS:Calculated results of the positive rates at the age of 0,6,18 and 56 are 17.7%,20.2%,12.7%and 3.1%respectively; the differences of H1N1 antibody positive rates in different age groups had statistical significance(X2= 65.618, P= 0.000). Results of the positive rates in male and female groups are 14.0%and 12.4%respectively; the differences of H1N1 antibody positive rates in different sexes had no statistical significance (X2= 1.162, P= 0.281). Results of the positive rates in different time points are 2.1%,14.8%,21.7%,14.8%, and 13.2%in succession, the differences of H1N1 antibody positive rates at different time points had statistical significance (X2= 72.999, P= 0.000). The average antibody titers in different groups of people at the ages of 0,6,18, and 56 were 49.65,55.68,60.63 and 46.41; the difference of average antibody titers in different age groups had no statistical significance (H= 7.439, P= 0.059); the average antibody titers at different time points from the first to the fifth were 58.79, 49.51,58.79,52.54 and 58.79; the difference of the average antibody titers at different time points had no statistical significance (H= 8.765, P= 0.067)。CONCLUSIONS:The serumal H1N1 antibody positive rate of the ordinary people in Shanxi Province is 13.3%(3.1%-20.2%), indicating that effective immune protection has not been built yet, and people are still at a susceptible state to H1N1 virus. Therefore, possibility still exists for the outbreak of pandemic H1N1 influenza when favorable condition appears, that is, precautions prior to prevailing seasons are still of great necessity. H1N1 antibody positive rates in different age groups are in positive correlation with the reported incidence level, which means natural infection serves as a major factor influencing the H1N1 antibody positive rate while the impact of past infection still remains to be confirmed. The actual number of infections calculated in the light of antibody positive rate has greatly outnumbered the reported number, presenting the fact that there exits large amount of symptomless infection and also mild cases, this is of positive significance in blocking the communication process. The trend of antibody positive rate over time shows that the level of antibody reaches the peak two months after peak incidence, then goes down indicating that the duration of H1N1 antibody in human serum may be short. Ages may affect the amount of antibody, but this effect is not that obvious. |
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