| Background:Influenza A(H1N1) Virus has widely spread in China,2009, Because lack of specific clinical manifestation, Only can be diagnosised through DNA testing and viruses isolated, Testing costs is high, These can't widely used for clinical diagnosis.At the time there were lots of light disease cases and recessive infection, Diagnosed cases in china information system for disease control and prevention can't reflect the actual situation of disease,so we must understand the actual infection levels of each age group in different time. It can be provide reliable scientific basis for perfecting epidemic prevention and control measures.and coping influenza pandemic. Chinese Center for Disease Control and Prevention formulated the survey scheme,reseached the status of influena A(H1N1) infection in china by the end of 2009. By the scheme,zibo City was abstracted as project in Shang Dong Provice.Objective:The investigation purposes is mainly to master the actual level of Influenza A(H1N1) Virus of different period,different regions,different groups; To master the dynamic change trend of different people in Zibo during influenza pandemic and to set up a scientific basis for prevention and control of influenza A(H1N1) epidemic.Materials and Methods:By multi-stage stratifieg randon sampling,Two counties was randomly selected from nine counties in Zibo as the project areas.then selected 2～5 street agency from every area,then selected again moderate residents' committees from Every street agency. Three cross-sectional survey has been conducted respectively in January, March to April, August to September in 2010. Each survey,about 150 objects has been drawed from each group age from 0-5,6-15,16-24,25-59,over 60 age groups in each countis,4500 surveis has been taken in three cross-sectional study.All the surveies identified were investigated by an uniform questionnaire and their blood samples were tested A(H1N1) influenza antibody by serum agglutination test, HI antibody titer≥1:40 were positive.All questionnaire were double entried Epidata 3.1 Database And using the consistency test.Using SPSS 13.0 software for statistical analysis, chi-square test was used to compare rates.Main results1,Positive rate of antibody of 4500 objects was 25.60%, natural infection rate was 21.09%, Ratio of apparent infection and silent infection was 1.97:1.Positive rate of man is 27.05%,is slightly higher than female, there was no statistical significance between different regions.2. There were 476 vaccines of influenza A(H1N1) in 4500 subjects, Accounted for 10.58% of investigation number, Antibody positive rate of vaccines was 42.65%,is higher than unvaccinated persons.that is 23.58%.3. Positive rate of antibody of the first investigation was higest in all subjects, vaccinated and unvaccinated. Positive rate of antibody gradually rose within 1 month after vaccined by influenza A(H1N1) vaccine,that was highest after 15～28 day,then antibody gradually decied over time, that of vaccine infection of influenza A(H1N1) after half past year was 11.36%.4. Positive rate of antibody of the age group from 16 to 24 in all subjects was the highest.33.99%.that of the age group more than sixty was the lowest,14.43%.5. Positive rate of antibody of teachers in all subjects was the higest,38.10%, then that of students.35.68%,medical staff relatively the lowest,18.09%.6. Positive rate of antibody of Influenza A H1N1 was 33.97% in Influenza vaccines at least 1 dose since 1997.that was higer than Uninoculated flu vaccine,22.54%. 7. The fevers accounted for 61.23%in all influenza A H1N1 infections, Cough symptoms accounted for 69.70%, sore throat symptoms accounted for 54.80%, all those symptoms have a share of 25.88%, all Infections are light disease cases.Conclusion and suggestion1. Positive rate of antibody of Influenza A H1N1 was 25.60%in this investigation,that is consistent as the positive of our national groups.Susceptibility and risk of infection is consistent between different regions for Influenza A H1N1. Influenza A H1N1 widely spread in our city in 2009, natural infection rate was 21.09%, the actual number of infections was far more than the number of confirmed cases.2. Epidemiological features of influenza A H1N1 is similar to seasonal influenza. The first,the group of school-age population and young people are the largest group infected; Second, there is a certain percentage of people who do not appear flu-like symptoms in infected people.3.Influenza A H1N1 vaccine inoculation has a good epidemiological protection effect, Seasonal flu vaccine may have some cross-protection for Influenza A H1N1, antibodies of seasonal H1N1 influenza may have a certain degree of protection in Specific populations for Influenza A H1N1.4. Positive rate of antibody all gradually decreased over time in all subjects, the vaccination of Influenza A H1N1 vaccine and those unvaccinated, Antibody levels in vaccinated decreased faster than the other two.5. Influenza vaccination and Influenza A H1N1 influenza vaccination can produce specific antibodies, raise the level of population immunity. Antibody levels declined with the passage of time after immunization, we recommend focus groups should vaccinate influenza vaccine annually.6. Expanding the scope of influenza monitoring, Conducting influenza surveillance Long-term and continuously can grasp the situation of influenza activity timely and accurately.It can provide a reliable basis for seasonal influenza epidemics, influenza pandemic.7. Regularly monitoring the level of the antibody of influenza in a crowd, can understand the immune protection for Epidemic strains of influenza and the changes in viral antigens, this measure can provide an important basis for the prevention and control of influenza. |
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