[Surveillance of immunization effectiveness and titer of type â and type â ¢ polio vaccine in Beijing before and after the adjustment of immunization strategy in 2012-2018].

Objective: To analyze the changing trend of polio vaccine immunization effectiveness and vaccine titer in Beijing in 2012, 2014, 2016 and 2018 before and after the adjustment of polio vaccine immunization program strategy. Methods: According to the convenient sampling method,the vaccination clinics of Chaoyang and Yanqing Districts in 2012, Fengtai and Daxing Districts in 2014, Tongzhou and Pinggu Districts in 2016, Dongcheng and Shunyi Districts in 2018 were selected as monitoring points. A total of 292 children were selected 4-8 weeks after the completion of 3 doses polio vaccine basic immunization which were 3 doses of trivalent oral poliovirus vaccine（tOPV）schedule before the strategy adjustment in 2012-2014 and 1 dose of inactivated poliovirus vaccine (IPV) following 2 doses of bivalent oral poliovirus vaccine (bOPV) sequential schedule after the adjustment in 2016-2018. About 1.0 ml blood samples were collected to detect type Ⅰ and Ⅲ neutralizing poliovirus antibody. A total of 9 oral poliovirus vaccines (8 vaccines in 2012) were selected from different sources of vaccine storage every year to test the vaccine titer using random number method. Results: The [M（P25，P75）] age of 292 children was 5 (5, 6) months, and the ratio of male to female was 1.04 (149/143). In 2012, 2014, 2016 and 2018, 66,72,68 and 86 children were investigated respectively. After basic immunization, antibody positive rates for type Ⅰ and Ⅲ poliovirus were 100%, except 98.61% (71) for type Ⅰ poliovirus in 2014. The neutralizing antibody titer of type Ⅰ and Ⅲ poliovirus was higher in 2016 and 2018 than that in 2012 and 2014 (P<0.001). The average titer of tOPV were (6.05±0.15) and (6.16±0.12) lgCCID50 per dose in 2012 and 2014. The average titer of bOPV were (6.88±0.21) and (6.26±0.14) lgCCID50 per 100 µl in 2016 and 2018 (P<0.001). Conclusion: Before and after the adjustment of polio vaccine immunization strategy in Beijing, the basic immunization success rate of the IPV-bOPV sequential immunization schedule was good as well as full tOPV schedule. The level of polio antibody produced by the IPV-bOPV sequential immunization schedule was higher. After adjustment, bOPV titer in 2016 was significantly higher than those before adjustment, while bOPV titer decreased significantly in 2018.

[Systematic reviews and evidence quality assessment on effectiveness of 1 dose varicella attenuated live vaccine for healthy children aged 1-12 years in China].

Objective: To assess the effectiveness of 1 dose varicella attenuated live vaccine (VarV) for healthy children aged 1-12 years in China and explore the application of the Grades of Recommendation, Assessment, Development, and Evaluation (GRADE) framework in observational studies of vaccine effectiveness (VE). Methods: We searched studies about the VE of 1-dose VarV for children aged 1-12 years in China which published before 2019 and evaluated the quality of the studies by the Newcastle Ottawa Scale (NOS) table. We used Meta-analysis models to obtain the pooled 1-dose VE and that in subgroups by study design, outbreak or not, study quality and age of subjects. The evidences of VEs were rated by means of the GRADE system. Results: Thirty-two studies were included and the pooled 1-dose VE was 75% [95% confidence interval (CI): 68%-80%]. The VE of outbreak studies [VE=66% (95%CI: 57%-73%)] was lower than non-outbreak studies [VE=85% (95%CI: 78%-89%)], and the VE in <6 years old children [VE=84% (95%CI:77%-89%)] was higher than that in ≥6 years old children [VE=60% (95%CI: 51%-68%)]. There was no significant difference in VE among studies with different design and quality. The quality of the evidences of pooled 1-dose VE was"very low", which was downgraded in bias risk and inconsistency and not downgraded in indirectness, imprecision and publication bias. Conclusions: The 1-dose VarV can provide medium level protection for 1-12 years old children in China, but it will decrease significantly for ≥6 years old children, so it is suggested to implement the strategies of two-dose vaccination of VarV in children <6 years old. The GRADE framework can be used in the observational studies of VE and it is suggested that the technical guidelines of observational study should be worked out to improve the overall quality of evidence.