[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.

An analysis on the surveillance results of safety of post-marketing immunization of varicella attenuated live vaccine in Henan Province / 预防医学

Objective To analyze the characteristics of adverse reactions for varicella attenuated live vaccine (VarV) in Henan Province from 2011 to 2016, in order to evaluate the immunization safety related to VarV. Methods The adverse reaction data and vaccination doses of VarV in Henan Province from 2011 to 2016 were collected through the China Information Management System for Immunization Programming. The descriptive methodology was used for data analysis. Results A total of 686 adverse reactions cases were reported in Henan Province from 2011 to 2016, and the average reported incidence rate was 16.89 per 100000 dose. The ratio of male to female was 1.14:1, and 80.61% cases occurred between 1 and 2 years old, and the reported incidence rate was 13.62 per 100000 dose. And 32.80% cases were reported from April to June, and the reported incidence rate was 5.54 per 100000 dose. The cases were mainly concentrated in Zhengzhou, Luoyang, Zhoukou and Xinyang. Most cases occurred after the first dose and within 1 d after vaccination. The main diagnoses of adverse reactions were fever, local swelling, indurations and transient anaphylactic disorders. The reported incidence rate of anaphylactic shock and fever convulsion were 0.37 per 100000 dose and 0.12 per 100000 dose respectively. All cases were recovered or got better. Conclusion The safety of VarV was good in Henan Province. However, the surveillance should focus on the anaphylactic shock and fever convulsion and other serious rare adverse reaction.

Post-marketing evaluation of the effectiveness and safety of a varicella attenuated live vaccine in ;China / 中华微生物学和免疫学杂志

Objective To evaluate the effectiveness and safety of varicella attenuated live vaccine ( VarV) produced by A Co. Ltd. Methods We selected 3 provinces in China and enrolled 15 002 children aged 3-<11 in this random, multicenter study. Participants were randomly divided into two groups: the ex-perimental group and the control group. Every varicella case was collected and recorded to calculate the vac-cine efficacy. Vaccine safety was assessed by means of spontaneous report and regular follow-up visits. Re-sults During the observation period, the incidence of varicella was 0. 147% in the experimental group and 1. 155% in the control group (P<0. 001). The vaccine efficacy was 87. 27%. The adverse reaction rate af-ter vaccination was lower than the rates reported in other literatures. Conclusion The VarV produced by A Co. , Ltd. in China was effective and safe in preventing varicella.

Outbreak of varicella in a highly vaccinated preschool population.

BACKGROUND: Varicella vaccine is available for private purchase in Beijing, with single dose recommended for children aged ≥12 months before 2013. Despite the success achieved in reducing varicella incidence, varicella outbreaks continued to occur, including in schools and kindergartens among highly vaccinated children. We investigated a varicella outbreak in a preschool with high varicella vaccination coverage in Haidian district, Beijing. METHODS: Through questionnaires, data including children's medical and vaccination history were collected from their parents. A case of varicella was defined as an acute, generalized, maculopapulovesicular rash without other apparent cause in a child in the preschool from March 10 through March 29, 2010. Attack rates in vaccinated and unvaccinated children were calculated, and the analyses of vaccine effectiveness (VE) and of risk factors for breakthrough disease (varicella occurring >42 days after vaccination) were conducted. RESULTS: A total of 12 cases occurred during the outbreak, and ten of them (83.3%) had breakthrough varicella. The index case with mild varicella occurred in a child who had been vaccinated four years previously. Questionnaires were returned for all of 150 children in the preschool. Of all the 150 children, 144 (96.0%) had no prior history of varicella disease. Among these children, 135(93.7%) had received single-dose varicella vaccine before the outbreak. VE was 84.5% [95% confidence interval (CI): 62.8%∼93.5%] in preventing varicella of any severity, and VE was 92.2% (95% CI: 81.4%∼96.8%) against moderate to severe varicella. Age at vaccination (<15 months vs. ≥15 months) and time since vaccination before the outbreak (<3 years vs. ≥3 years) were not associated with the increased risk of breakthrough varicella(P=0.124 and 1, respectively). All the varicella cases with vaccination history verified through immunization records had received varicella vaccine and measles-mumps-rubella vaccine >30 days apart. CONCLUSIONS: Breakthrough infection with fever in vaccinated person may be as infectious as varicella in unvaccinated persons. High single-dose varicella vaccination coverage is effective in reducing varicella incidence, but not sufficient to prevent outbreak. To control varicella outbreak a second dose may deserve additional consideration.

Analysis of the safety surveillance data of adverse events following immunization with varicella atten-uated live vaccine in Hebei province, 2012-2014 / 中华微生物学和免疫学杂志

Objective To analyze the characteristics of adverse events following immunization ( AEFI) with varicella attenuated live vaccine ( VarV) in Hebei province during 2012—2014, to evaluate the safety of VarV and to provide supportive evidences for planning chicken pox prevention and control strate-gies in Hebei province.Methods The AEFI data associated with VarV in Hebei province during 2012 to 2014 were collected from the national AEFI information management system and were analyzed by using the method of descriptive epidemiology.Results A total of 239 cases reported during 2012 to 2014 were col-lected from the national AEFI information management system, with a male to female ratio of 1.44 ∶1.The estimated incidence rate was 25.51 per 100 000 doses.One case was serious AEFI with an incidence rate of 0.11 per 100 000 doses.Most of the AEFI cases were children under 3 years old and identified in scattered inhibiting children and kindergarten kids.The main symptoms of common vaccine reactions were fever, local swelling and induration .The rare vaccine reactions were presented as anaphylactic rashes .Conclusion The reported incidence rate of VarV associated AEFI in Hebei province was less than expected.However, the estimated incidence rate of common vaccine reactions in Hebei province was higher than that showed on the Analysis on Surveillance Data of Post-marketing Immunization Safety for Varicella Attenuated Live Vac-cine in China, 2010—2012.Attentions to the AEFI after immunization with VarV should also be paid in fu-ture.

Monitoring analysis of the titers of varicella attenuated live vaccines in Minhang District, Shanghai / 中华微生物学和免疫学杂志

Objective To measure the titers of varicella live attenuated vaccines ( VarV) during the process of transportation and storage in different seasons and communities of Minhang Distract, Shang-hai, to evaluate the operation of cold chain system and the thermal stability of vaccines and to provide refer-ences for the management, introduction, research and development of vaccine in future.Methods Four communities with high outbreak rates of varicella during 2012 to 2013 and four communities with low out-break rates were randomly selected from 13 communities in Minhang District, Shanghai.The titers of VarVs were detected by using the quantitative plaque assay before and after 30 days of storage in November 2013 and February, May, August 2014.Results The overall rate of qualified VarVs was 90.63% with a geo-metric mean titer (GMT) of 3.67 (LgPFU/0.5 ml).96.88%of the VarVs produced by company C met the quality standard with a GMT of 3.89 ( LgPFU/0.5 ml) followed by those produced by company B with a rate of 91.67%and a GMT of 3.75 ( LgPFU/0.5 ml) .The rate of qualified VarVs produced by company A was the lowest, which was 80.00%, with GMT of 3.29 (LgPFU/0.5 ml).There were significant differences in the rates of qualified VarV among the three companies (χ2=8.288, P=0.016).The rate of qualified vac-cines in communities close to the Shanghai Minhang Center for Disease Control and Prevention ( Minhang CDC) was 91.67%, while 100%of the vaccine samples collected form the communities at a middling dis-tance from or far from the Minhang CDC met the quality standard.No significant difference in the rate of qualified vaccine was found among the three types of communities (χ2=3.441, P=0.179).The quarterly rates of qualified vaccines produced by B and C companies were 100%except for the third quarter.The rates of qualified vaccines produced by A, B and C companies in the third quarter were respectively 70.00%, 66.67%and 87.50%.No statistical differences in the quarterly rates of qualified vaccines were found among the three companies (χ2=1.25, P=0.7412;χ2=6.545, P=0.088; χ2=6.194, P=0.103).No statistical differences in the rates of qualified vaccines before and after 30 days of storage were found among the three companies (χ2=0.625, P=0.347;χ2=0.000, P=1.000;χ2=2.065, P=0.492).Conclusion A well-managed and-operated cold chain system was implemented in Minhang District in the storage and transport of vaccines as well as other related links.The thermal stability of vaccines produced by company C was better than those of the other two companies.A surveillance for the titers of vaccines produced by com-pany A should be strengthened.