扩大免疫对福建省人群风疹病毒抗体水平分布的影响

Effect of expanded immunization on distribution of antibody level against rubella virus among population in Fujian Province,China

目的在不同时期开展人群风疹病毒抗体水平监测,以评估风疹疫苗纳入扩大免疫策略的实施效果。方法在2009、2011和2019年分别按分层随机抽样原则,调查福建省0~60岁一般人群,并采集静脉血标本。采用定量ELISA法检测风疹病毒IgG抗体水平,分析比较不同时期人群风疹病毒抗体水平的分布特征变化。结果2009、2011和2019年人群风疹病毒IgG抗体阳性率分别为64.16%、68.00%和70.10%,抗体几何平均浓度(geometric mean concentration,GMC)分别为20.97、28.72和27.91 IU/mL。实施扩大免疫11年后的2019年,人群风疹病毒抗体水平已较2009年显著提高(Z=2.91,P<0.01),尤其是8月龄~10岁扩大免疫服务对象含风疹疫苗(rubella-containing vaccine,RCV)接种率达95.22%,抗体阳性率达79.39%,GMC为36.98(95%CI:35.51~38.50)IU/mL,显著高于2009年同一年龄组[64.68%和21.21(95%CI:19.07~23.54)IU/mL](χ2=95.23,P<0.01;F=129.61,P<0.01)。2019年福建省人群风疹病毒抗体水平年龄组分布模式已从2009和2011年免疫不充分情况下自然感染模式转变为疫苗免疫模式,扩大免疫服务对象获得了高免疫水平,10~19岁非扩大免疫对象抗体水平(抗体阳性率为52.92%,GMC为18.42 IU/mL)低于2009和2011年同年龄组,为发病的高风险人群。2019年免疫服务对象在1岁组风疹病毒抗体水平达到最高(95.66%和64.17 IU/mL)后,随年龄增长,抗体阳性率和GMC分别以平均每年6.65%和12.09%速度下降,至6岁组时降至较低水平(62.41%和25.38 IU/mL)。结论RCV扩大免疫服务对象风疹病毒抗体水平升高显著,但免疫获得的抗体水平随年龄增长呈下降趋势;部分非免疫对象因抗体水平较低而成为高风险发病人群,因此需继续加强免疫水平监测,并及时根据抗体水平衰减情况调整免疫策略措施。

Objective To monitor the antibody levels against rubella virus in population in various periods so as to evaluate the implementation effect of inclusion of rubella-containing vaccine(RCV)in the Expanded Immunization Program(EPI).Methods In 2009,2011 and 2019,general population aged 0~60 years in Fujian Province were investigated by stratified random sampling,of whom the venous blood samples were collected and determined for IgG antibody level against rubella virus by ELISA,and the distribution characteristics of rubella antibody level in various periods were analyzed and compared.Results In 2009,2011 and 2019,the positive rates of IgG antibody against rubella virus in the investigated population were 64.16%,68.00%and 70.10%,while the geometric mean concentrations(GMC)were 20.97,28.72 and 27.91 IU/mL,respectively.However,in 2019,11 years after the implementation of EPI,the antibody level against rubella virus in population was significantly higher than that in 2009(Z=2.91,P<0.01),especially in those aged 8 months to 10 years,the coverage rate of rubella-containing vaccine(RCV)was 95.22%,while the antibody positive rate was 79.39%,and the GMC was 36.98(95%CI:35.51~38.50)IU/mL,which were significantly higher than those of the same age group in 2009[64.68%and 21.21(95%CI:19.07~23.54)IU/mL](χ2=95.23,P<0.01;F=129.61,P<0.01).In 2019,the age group distribution pattern of rubella antibody level in population of Fujian Province had changed from natural infection mode under the condition of inadequate immunization in 2009 and 2011 to vaccine immunization mode,and high immunity level was obtained in the subjects of EPI service.However,non-EPI subjects aged 10~19 years showed a lower antibody level(an antibody positive rate of 52.92%and a GMC of 18.42 IU/mL)than the same age group in 2009 and 2011,which was a high-risk population of incidence of rubella.The rubella antibody level in 1-year-old group reached the maximum(an antibody positive rate of 95.66%and a GMC of 64.17 IU/mL)in 2019,which decreased with increasing age at annual average rates of 6.65%and 12.09%respectively and decreased to a low level in 6-year-old group(62.41%and 25.38 IU/mL).Conclusion Rubella antibody level in RCV EPI subjects increased significantly,while the antibody level acquired by immunization decreased with age.Partial non-EPI subjects were at high risk due to low antibody level,therefore,it is necessary to further strengthen the monitoring of immune level and timely adjust the immunization strategies according to the attenuation of antibody level.