Relative vaccine effectiveness against Delta and Omicron COVID-19 after homologous inactivated vaccine boosting: a retrospective cohort study
Rui Zhang,
Dan Wu,
Lin Tang,
Ying Ye,
Haifeng Wang,
Zhijie An,
Lance Rodewald,
Fuzhen Wang,
Zundong Yin,
Yanyang Zhang,
Zhao-Hui Qian,
Ai-Bin Wang,
Chang Huang,
Mingxia Lu,
Changshuang Wang,
Ya-Ting Ma,
Jingjing Pan,
Ya-fei Li,
Xiao-Ya Lv,
Xuan-Yi Wang,
Yi-Ming Shao,
Zhi-Yin Wu
Affiliations
Rui Zhang
National Center for Clinical Laboratories, Beijing Hospital, National Center of Gerontology; Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, Beijing, China
Dan Wu
National Immunization Program, Chinese Center for Disease Control and Prevention, Beijing, China
Lin Tang
National Immunization Program, Chinese Center for Disease Control and Prevention, Beijing, China
Ying Ye
Department of Communicable Disease Control and Prevention, Henan Provincial Center for Disease Control and Prevention, Zhengzhou, Henan, China
Haifeng Wang
Department of Communicable Disease Control and Prevention, Henan Provincial Center for Disease Control and Prevention, Zhengzhou, Henan, China
Zhijie An
National Immunization Program, Chinese Center for Disease Control and Prevention, Beijing, China
Lance Rodewald
National Immunization Program, Chinese Center for Disease Control and Prevention, Beijing, China
Fuzhen Wang
National Immunization Program, Chinese Center for Disease Control and Prevention, Beijing, China
Zundong Yin
National Immunization Program, Chinese Center for Disease Control and Prevention, Beijing, China
Yanyang Zhang
Department of Henan Immunization Program, Henan Center for Disease Control and Prevention, Zhengzhou, Henan, China
Zhao-Hui Qian
NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
Ai-Bin Wang
Beijing Ditan Hospital Capital Medical University, Beijing, China
Chang Huang
National Immunization Program, Chinese Center for Disease Control and Prevention, Beijing, China
Mingxia Lu
Department of Henan Immunization Program, Henan Center for Disease Control and Prevention, Zhengzhou, Henan, China
Changshuang Wang
Department of Henan Immunization Program, Henan Center for Disease Control and Prevention, Zhengzhou, Henan, China
Ya-Ting Ma
Department of Henan Immunization Program, Henan Center for Disease Control and Prevention, Zhengzhou, Henan, China
Jingjing Pan
Department of Communicable Disease Control and Prevention, Henan Provincial Center for Disease Control and Prevention, Zhengzhou, Henan, China
Ya-fei Li
Department of Communicable Disease Control and Prevention, Henan Provincial Center for Disease Control and Prevention, Zhengzhou, Henan, China
Xiao-Ya Lv
Development Center for Medicine and Science & Technology, National Health Commission, Beijing, China
Xuan-Yi Wang
Shanghai Institute of Infectious Disease and Biosecurity, Key Laboratory of Medical Molecular Virology of Minstry of Eduation & Ministry of Health, and Institutes of Biomedical Sciences, Shanghai Medical College, Fudan University, Shanghai, China
Yi-Ming Shao
State Key Laboratory of Infectious Disease Prevention and Control, National Center for AIDS/STD Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
Zhi-Yin Wu
Development Center for Medicine and Science & Technology, National Health Commission, Beijing, China
Design Retrospective cohort studyMethods We evaluated relative vaccine effectiveness (rVE) with a retrospective cohort study of close contacts of infected individuals using a time-dependent Cox regression model. Demographic and epidemiologic data were obtained from the local Centers for Disease Control and Prevention; clinical and laboratory data were obtained from COVID-19-designated hospitals. Vaccination histories were obtained from the national COVID-19 vaccination dataset. All data were linked by national identification number.Results Among 784 SARS-CoV-2 infections, 379 (48.3%) were caused by Delta and 405 (51.7%) were caused by Omicron, with breakthrough rates of 9.9% and 17.8%, respectively. Breakthrough rates among boosted individuals were 8.1% and 4.9%. Compared with subjects who received primary vaccination series ≥180 days before infection, Cox regression modelling showed that homologous inactivated booster vaccination was statistically significantly associated with protection from symptomatic infection caused by Omicron (rVE 59%; 95% CI 13% to 80%) and pneumonia caused by Delta (rVE 62%; 95% CI 34% to 77%) and Omicron (rVE 87%; 95% CI 3% to 98%).Conclusions COVID-19 vaccination in China provided good protection against symptomatic COVID-19 and COVID-19 pneumonia caused by Delta and Omicron variants. Protection declined 6 months after primary series vaccination but was restored by homologous inactivated booster doses given 6 months after the primary series.
