Analysis of measles immunity level in persistent populations in Beijing, 2012 / 中华预防医学杂志

<p><b>OBJECTIVE</b>To analyze the measles immunity level of persistent population in Beijing.</p><p><b>METHODS</b>A total of 2125 objects from 10 age groups, who had been living in Beijing for over 6 months, were selected from urban and rural areas in Beijing in 2012. Demographic characteristics, history of measles and vaccine immunization were investigated by questionnaire. 5 ml blood sample of each subject was collected, and the Measles IgG antibody was measured by ELISA assay.</p><p><b>RESULTS</b>Positive rate of measles antibody was 84.71% (1800/2125) and standardized positive rate was 88.07% . Median of antibody was 960.46 IU/L. Positive rate and median of measles antibody were significantly different between population from different age groups (χ(2) = 341.60, P < 0.01; H = 216.27, P < 0.01). Antibody positive rate and median were lowest in the <1 year age group, which were separately 43.06% (90/209) and 185.80 IU/L; and highest in the 1-4 (97.31% (181/186) and 2448.81 IU/L) and 5-9 years age group (96.46% (218/226) and 1910.72 IU/L). The range of antibody positive rate and median in adults of ≥ 15 years were 81.98%-90.14% and 744.38-1474.84 IU/L. Antibody positive rate and median in persistent population, which were separately 82.45% (883/1071) and 899.82 IU/L, were lower than those in migrant population, which were 87.00% (917/1054) and 166.19 IU/L, respectively (χ(2) = 8.51, P < 0.01;U = 538 704.00, P < 0.01). Antibody positive rate and median in population with vaccination history, which were separately 91.95% (891/969) and 1443.11 IU/L, were higher than those population without vaccination history and people whose history unknown (32.95% (57/173) , 127.33 IU/L; 86.67% (852/983) , 923.73 IU/L). The difference showed statistical significance (χ(2) = 399.92, P < 0.01; H = 202.11, P < 0.01).</p><p><b>CONCLUSION</b>Among the persistent population in China, measles antibody level among the children aging 1-9 years old was high enough to prevent outbreak and epidemic of measles. However, we should try our best to strengthen the measles antibody level among the babies younger than 1 year old and the migrant population aging between 15 and 40 years old.</p>

Effectiveness on post-exposure vaccination of varicella and its influencing factors in elementary schools in Beijing / 中华流行病学杂志

Objective To evaluate the effectiveness of post-exposure varicella vaccination in elementary schools in Beijing and to explore its influencing factors. Methods From May to July 2007, variceila cases from 49 elementary schools in 4 districts in Beijing were observed prospectively. The study included 7882 children who were from the same classrooms, same floor or same bungalow areas with the varicella cases. Vaccination status, history on varicella and onset of rashes were collected to calculate the secondary attack rate among those children under observation and then the effectiveness of vaccine was calculated. Results The protection rate on post-exposure vaccination among children under observation was 85.26%. The rates were higher when the 1st case had received varicella vaccine before the onset, vaccines were administered soon after the exposure or there were less varicella cases occurred in the schools. For children in the same class, same floor or bungalow with varicella cases before post-exposure vaccination, the average rates of protection by vaccination were 84.26% and 87.06%, respectively. When the 1st case had received varicella vaccine prior to the onset, the post-exposure protection rates reached 92.09% and 93.06%, respectively, higher than that of the case when the 1st case had received no vaccination. When the administration of vaccine right after the occurrence of first varicella case, the rates of the effectiveness of vaccine were 83.09% and 93.02%, both of which were higher than that of vaccine administered after the occurrence of 2 or 3 cases. When the vaccine administration of vaccination combined with the isolation of the already infected cases or within 5 days after the onset of the 1st case, the vaccine effectiveness could reach 86.60% and 92.73%, both were higher than otherwise. However, in those schools that bungalows were used as classrooms but without bus, canteen from school or student lodgings, it seemed that post exposure vaccination was more effective in preventing varicella from occurring. Conclusion Varicella vaccination after exposure in elementary schools in Beijing was effective in prevention and control of the disease. Immediate administration together with the isolation of cases could maximize the effectiveness of the vacine.