{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,24]],"date-time":"2026-02-24T18:01:04Z","timestamp":1771956064671,"version":"3.50.1"},"reference-count":32,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2026,2,24]],"date-time":"2026-02-24T00:00:00Z","timestamp":1771891200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Sinovac Biotech Co., Ltd."}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Vaccines"],"abstract":"<jats:p>Background\/Objectives: Varicella is a highly contagious childhood disease that may cause severe complications in susceptible populations. The SV-1 cell line-based varicella vaccine (VarV [SV-1]) has been increasingly used in routine immunization; however, safety and reporting patterns during the transition from partial use to full Expanded Program on Immunization (EPI) implementation remain poorly characterized. This study aimed to evaluate the safety profile and reporting dynamics of VarV (SV-1) before and after its incorporation into the Expanded Program on Immunization in Jiangsu Province, China. Methods: A retrospective observational study was conducted using data from the Jiangsu Provincial Immunization Integrated Service Management Information System and the Chinese National Adverse Event Following Immunization (AEFI) Information System (CNAEFIS), including all reported AEFI following VarV (SV-1) vaccination among children under 6 years of age during 2021\u20132023. Temporal trends, distribution characteristics, and factors associated with AEFI reporting were assessed using descriptive analyses, negative binomial (NB) regression models, and interrupted time series (ITS) analysis. Results: A total of 1,208,500 doses of VarV (SV-1) were administered, and 634 AEFI cases were reported, corresponding to an overall reporting rate of 52.46 per 100,000 doses. Most reported events were mild, self-limiting common reactions, predominantly pyrexia and injection-site reactions. No serious adverse events were identified. Although no immediate level change was observed at EPI implementation, a significant increasing post-EPI trend was detected, consistent with enhanced surveillance sensitivity rather than a change in intrinsic vaccine safety. Abnormal reactions were rare and resolved without sequelae. Conclusions: AEFI reporting rates following VarV (SV-1) vaccination in Jiangsu Province were within expected ranges, predominantly mild and reversible. Findings support the favorable safety profile of the VarV (SV-1) in routine childhood immunization programs and provide real-world evidence to support continued implementation of the two-dose varicella vaccination strategy within the EPI.<\/jats:p>","DOI":"10.3390\/vaccines14030200","type":"journal-article","created":{"date-parts":[[2026,2,24]],"date-time":"2026-02-24T16:58:18Z","timestamp":1771952298000},"page":"200","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Safety of an SV-1 Cell Line-Based Varicella Vaccine Before and After Integration into the Expanded Program on Immunization: A Real-World Study in Jiangsu Province, China"],"prefix":"10.3390","volume":"14","author":[{"given":"Jing","family":"Yu","sequence":"first","affiliation":[{"name":"Department of Immunization Program, Jiangsu Provincial Center for Disease Control and Prevention, Nanjing 210009, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6851-0435","authenticated-orcid":false,"given":"Yurong","family":"Li","sequence":"additional","affiliation":[{"name":"Sinovac Biotech Co., Ltd., Beijing 100085, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Zhiguo","family":"Wang","sequence":"additional","affiliation":[{"name":"Department of Immunization Program, Jiangsu Provincial Center for Disease Control and Prevention, Nanjing 210009, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0030-7016","authenticated-orcid":false,"given":"Xiang","family":"Sun","sequence":"additional","affiliation":[{"name":"Department of Immunization Program, Jiangsu Provincial Center for Disease Control and Prevention, Nanjing 210009, China"},{"name":"School of Public Health, Nanjing Medical University, Nanjing 211166, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Guodong","family":"Kang","sequence":"additional","affiliation":[{"name":"Department of Immunization Program, Jiangsu Provincial Center for Disease Control and Prevention, Nanjing 210009, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Borong","family":"Xu","sequence":"additional","affiliation":[{"name":"Department of Immunization Program, Jiangsu Provincial Center for Disease Control and Prevention, Nanjing 210009, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5380-1894","authenticated-orcid":false,"given":"Yuanyuan","family":"Zhu","sequence":"additional","affiliation":[{"name":"Department of Immunization Program, Jiangsu Provincial Center for Disease Control and Prevention, Nanjing 210009, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Xun","family":"Li","sequence":"additional","affiliation":[{"name":"Department of Immunization Program, Jiangsu Provincial Center for Disease Control and Prevention, Nanjing 210009, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Xiaozhe","family":"Song","sequence":"additional","affiliation":[{"name":"Department of Immunization Program, Xuzhou Center for Disease Control and Prevention, Xuzhou 221018, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yonghong","family":"Sun","sequence":"additional","affiliation":[{"name":"Department of Immunization Program, Xuzhou Center for Disease Control and Prevention, Xuzhou 221018, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Dongsheng","family":"Liu","sequence":"additional","affiliation":[{"name":"Department of Immunization Program, Xuzhou Center for Disease Control and Prevention, Xuzhou 221018, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yuan","family":"Ren","sequence":"additional","affiliation":[{"name":"Sinovac Biotech Co., Ltd., Beijing 100085, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Xueyan","family":"Sha","sequence":"additional","affiliation":[{"name":"Sinovac (Dalian) Vaccine Technology Co., Ltd., Dalian 116100, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ran","family":"Hu","sequence":"additional","affiliation":[{"name":"Department of Immunization Program, Jiangsu Provincial Center for Disease Control and Prevention, Nanjing 210009, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2026,2,24]]},"reference":[{"key":"ref_1","unstructured":"World Health Organization (2025). WHO position paper on varicella vaccines\u2014November 2025. Wkly. Epidemiol. Rec., 100, 567\u2013590."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"2211465","DOI":"10.1080\/21645515.2023.2211465","article-title":"Seroprevalence rates in children aged 3-6 years after implementing a two-dose varicella vaccination: A observational study","volume":"19","author":"Zhang","year":"2023","journal-title":"Hum. Vaccines Immunother."},{"key":"ref_3","first-page":"634","article-title":"Impact of inclusion of varicella vaccine into the immunization program on the incidence of varicella","volume":"35","author":"Liu","year":"2023","journal-title":"Shanghai J. Prev. Med."},{"key":"ref_4","unstructured":"Jiangsu Provincial Health Commission (2022). Notice on Incorporating Varicella Attenuated Live Vaccine into the Provincial Children\u2019s Immunization Program, Government Notice. (In Chinese)."},{"key":"ref_5","unstructured":"World Health Organization (2022). Global Vaccine Safety Blueprint 2.0 (GVSB2.0) 2021\u20132023, World Health Organization."},{"key":"ref_6","unstructured":"World Health Organization (2021). Causality Assessment of an Adverse Event Following Immunization (AEFI): User Manual for the Revised WHO Classification, World Health Organization. [2nd ed.]. 2019 update."},{"key":"ref_7","unstructured":"Wang, Y., Wang, L., L\u00fc, Z., Li, Y., Zhang, Y., Gao, Q., Dong, S., and Yin, W. (2013). A Diploid Human Embryonic Lung Fibroblast Cell Line SLF-1 and Its Application. (103255102A), CN Patent, Available online: https:\/\/patents.google.com\/patent\/CN103255102A\/zh."},{"key":"ref_8","unstructured":"National Health Commission of the People\u2019s Republic of China, and National Medical Products Administration (2022). Notice on Revising Selected Contents of the National Surveillance Program for Suspected Adverse Events Following Immunization, Document No. 208."},{"key":"ref_9","first-page":"356","article-title":"Surveillance of suspected adverse events following varicella attenuated live vaccine immunization in China, 2014\u20132020","volume":"28","author":"Li","year":"2022","journal-title":"Chin. J. Vaccines Immun."},{"key":"ref_10","first-page":"208","article-title":"Surveillance of suspected adverse events following immunization in China, 2020","volume":"28","author":"Zhang","year":"2022","journal-title":"Chin. J. Vaccines Immun."},{"key":"ref_11","first-page":"470","article-title":"Surveillance of suspected adverse events following immunization in China, 2021\u20132022","volume":"30","author":"Zhang","year":"2024","journal-title":"Chin. J. Vaccines Immun."},{"key":"ref_12","first-page":"121","article-title":"Surveillance of suspected adverse events following immunization in China, 2023","volume":"31","author":"Zhang","year":"2025","journal-title":"Chin. J. Vaccines Immun."},{"key":"ref_13","first-page":"564","article-title":"Varicella vaccination coverage among children aged 1\u20136 years and surveillance of suspected adverse events following immunization in Jiangsu Province, 2021\u20132022","volume":"29","author":"Zhang","year":"2023","journal-title":"Chin. J. Vaccines Immun."},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Zhang, L., Fu, Y., Wang, W., Liu, Y., Hu, R., Wang, Z., and Sun, X. (2024). Surveillance of adverse events following varicella vaccine immunization in Jiangsu Province, China, 2017\u20132023. BMC Infect. Dis., 24.","DOI":"10.1186\/s12879-024-09903-y"},{"key":"ref_15","first-page":"1667","article-title":"Safety of freeze-dried live attenuated varicella vaccine","volume":"25","author":"Li","year":"2012","journal-title":"Chin. J. Biol."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"1271","DOI":"10.1001\/jama.284.10.1271","article-title":"Postlicensure safety surveillance for varicella vaccine","volume":"284","author":"Wise","year":"2000","journal-title":"JAMA"},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Zhu, Y., Li, Y., Yu, J., Xu, B., Li, X., Hu, R., Song, X., Sun, Y., Liu, D., and Ren, Y. (2026). Safety Evaluation of Large-Scale Administration of a Novel Human Diploid (SV-1) Cell Line-Derived Varicella Attenuated Live Vaccine in Children 7\u201312 Years Old. Vaccines, 14.","DOI":"10.3390\/vaccines14010019"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"126535","DOI":"10.1016\/j.vaccine.2024.126535","article-title":"Vaccine safety surveillance in South Africa through COVID-19: A journey to systems strengthening","volume":"46","author":"Sankar","year":"2024","journal-title":"Vaccine"},{"key":"ref_19","first-page":"461","article-title":"Observation of adverse reactions following varicella attenuated live vaccine immunization among healthy children aged 1\u201312 years in parts of Anhui Province","volume":"30","author":"Wang","year":"2024","journal-title":"Chin. J. Vaccines Immun."},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Centers for Disease Control and Prevention (2023). Progress in immunization safety monitoring\u2014Worldwide, 2020\u20132022. MMWR Morb. Mortal. Wkly. Rep., 72, 1321\u20131326.","DOI":"10.15585\/mmwr.mm7249a2"},{"key":"ref_21","unstructured":"World Health Organization (2016). Global Manual on Surveillance of Adverse Events Following Immunization (2016 Update), World Health Organization. Available online: https:\/\/www.who.int\/publications\/i\/item\/9789241507769."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"3823","DOI":"10.1080\/21645515.2021.1939621","article-title":"Analysis of adverse events following immunization in Zhejiang, China, 2019: A retrospective cross-sectional study based on the passive surveillance system","volume":"17","author":"Pan","year":"2021","journal-title":"Hum. Vaccin. Immunother."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"1026","DOI":"10.1016\/j.cmi.2018.12.033","article-title":"Efficacy, safety and immunogenicity of live attenuated varicella vaccine in healthy children in China: Double-blind, randomized, placebo-controlled clinical trial","volume":"25","author":"Hao","year":"2019","journal-title":"Clin. Microbiol. Infect."},{"key":"ref_24","doi-asserted-by":"crossref","unstructured":"Serbanescu-Kele Apor de Zal\u00e1n, C., Bouwman, M., van Osch, F., Damoiseaux, J., Funnekotter-van der Snoek, M.-A., Verduyn Lunel, F., Van Hunsel, F., and de Vries, J. (2024). Changes in local and systemic adverse effects following primary and booster immunisation against COVID-19 in Dutch healthcare workers vaccinated with BNT162b2. Vaccines, 12.","DOI":"10.3390\/vaccines12010039"},{"key":"ref_25","first-page":"1173","article-title":"Post-marketing safety of live attenuated varicella vaccine in Zhejiang Province, China","volume":"30","author":"Li","year":"2017","journal-title":"Chin. J. Biol."},{"key":"ref_26","first-page":"1364","article-title":"Safety, immunogenicity, and lot-to-lot consistency of a live attenuated varicella vaccine (Oka strain) in healthy children: A randomized Phase III study","volume":"14","author":"Huang","year":"2018","journal-title":"Hum. Vaccines Immunother."},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Nazaire-Bermal, N., Jia, N., Maronilla, M.A.C., Lopez, J.F., Zeng, G., Wu, W., Nimo, A.B.C., Luan, C., and Xin, Q. (2025). Immunogenicity and Safety of a Live Attenuated Varicella Vaccine in Healthy Children Aged 12 to 15 Months: A Phase III, Randomized, Double-Blind, Active-Controlled Clinical Trial. Vaccines, 13.","DOI":"10.3390\/vaccines13090973"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"2161789","DOI":"10.1080\/21645515.2022.2161789","article-title":"Immunogenicity and safety of a live attenuated varicella vaccine co-administered with inactive hepatitis A vaccine: A phase 4, single-center, randomized, controlled trial","volume":"19","author":"Sun","year":"2023","journal-title":"Hum. Vaccines Immunother."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"108212","DOI":"10.1016\/j.ijid.2025.108212","article-title":"Immunogenicity and safety of varicella vaccine co-administered with seasonal influenza vaccine in healthy children aged 7-12 years in China","volume":"162","author":"Sun","year":"2026","journal-title":"Int. J. Infect. Dis."},{"key":"ref_30","doi-asserted-by":"crossref","unstructured":"Wang, Y., Lei, X., Huang, L., Ma, Y., Yuan, H., Zhao, D., and Meng, F. (2025). Immune Persistence Following a Single Dose of Varicella Vaccine: 5-Year and 8-Year Follow-Up of a Phase 3, Randomized, Double-Blind, Placebo-Controlled Trial. Vaccines, 13.","DOI":"10.3390\/vaccines13101024"},{"key":"ref_31","first-page":"120","article-title":"The practices and experiences of Jiangsu Province taking the lead in incorporating the 2-dose varicella vaccine immunization schedule into the local immunization program","volume":"60","author":"Sun","year":"2026","journal-title":"Chin. J. Prev. Med."},{"key":"ref_32","first-page":"213","article-title":"Progress towards the varicella vaccination in China","volume":"60","author":"Fu","year":"2026","journal-title":"Chin. J. Prev. Med."}],"container-title":["Vaccines"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2076-393X\/14\/3\/200\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,2,24]],"date-time":"2026-02-24T17:04:15Z","timestamp":1771952655000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2076-393X\/14\/3\/200"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,2,24]]},"references-count":32,"journal-issue":{"issue":"3","published-online":{"date-parts":[[2026,3]]}},"alternative-id":["vaccines14030200"],"URL":"https:\/\/doi.org\/10.3390\/vaccines14030200","relation":{},"ISSN":["2076-393X"],"issn-type":[{"value":"2076-393X","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,2,24]]}}}