• Shengli Xia, Kai Duan, Yuntao Zhang, Dongyang Zhao, Huajun Zhang, Zhiqiang Xie, Xinguo Li, Cheng Peng, Yanbo Zhang, Wei Zhang, Yunkai Yang, Wei Chen, Xiaoxiao Gao, Wangyang You, Xuewei Wang, Zejun Wang, Zhengli Shi, Yanxia Wang, Xuqin Yang, Lianghao Zhang, Lili Huang, Qian Wang, Jia Lu, Yongli Yang, Jing Guo, Wei Zhou, Xin Wan, Cong Wu, Wenhui Wang, Shihe Huang, Jianhui Du, Ziyan Meng, An Pan, Zhiming Yuan, Shuo Shen, Wanshen Guo, and Xiaoming Yang.
• Henan Center for Disease Control and Prevention, Zhengzhou, Henan, China.
• JAMA. 2020 Sep 8; 324 (10): 951-960.

ImportanceA vaccine against coronavirus disease 2019 (COVID-19) is urgently needed.ObjectiveTo evaluate the safety and immunogenicity of an investigational inactivated whole-virus COVID-19 vaccine in China.InterventionsIn the phase 1 trial, 96 participants were assigned to 1 of the 3 dose groups (2.5, 5, and 10 μg/dose) and an aluminum hydroxide (alum) adjuvant-only group (n = 24 in each group), and received 3 intramuscular injections at days 0, 28, and 56. In the phase 2 trial, 224 adults were randomized to 5 μg/dose in 2 schedule groups (injections on days 0 and 14 [n = 84] vs alum only [n = 28], and days 0 and 21 [n = 84] vs alum only [n = 28]).Design, Setting, And ParticipantsInterim analysis of ongoing randomized, double-blind, placebo-controlled, phase 1 and 2 clinical trials to assess an inactivated COVID-19 vaccine. The trials were conducted in Henan Province, China, among 96 (phase 1) and 224 (phase 2) healthy adults aged between 18 and 59 years. Study enrollment began on April 12, 2020. The interim analysis was conducted on June 16, 2020, and updated on July 27, 2020.Main Outcomes And MeasuresThe primary safety outcome was the combined adverse reactions 7 days after each injection, and the primary immunogenicity outcome was neutralizing antibody response 14 days after the whole-course vaccination, which was measured by a 50% plaque reduction neutralization test against live severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).ResultsAmong 320 patients who were randomized (mean age, 42.8 years; 200 women [62.5%]), all completed the trial up to 28 days after the whole-course vaccination. The 7-day adverse reactions occurred in 3 (12.5%), 5 (20.8%), 4 (16.7%), and 6 (25.0%) patients in the alum only, low-dose, medium-dose, and high-dose groups, respectively, in the phase 1 trial; and in 5 (6.0%) and 4 (14.3%) patients who received injections on days 0 and 14 for vaccine and alum only, and 16 (19.0%) and 5 (17.9%) patients who received injections on days 0 and 21 for vaccine and alum only, respectively, in the phase 2 trial. The most common adverse reaction was injection site pain, followed by fever, which were mild and self-limiting; no serious adverse reactions were noted. The geometric mean titers of neutralizing antibodies in the low-, medium-, and high-dose groups at day 14 after 3 injections were 316 (95% CI, 218-457), 206 (95% CI, 123-343), and 297 (95% CI, 208-424), respectively, in the phase 1 trial, and were 121 (95% CI, 95-154) and 247 (95% CI, 176-345) at day 14 after 2 injections in participants receiving vaccine on days 0 and 14 and on days 0 and 21, respectively, in the phase 2 trial. There were no detectable antibody responses in all alum-only groups.Conclusions And RelevanceIn this interim report of the phase 1 and phase 2 trials of an inactivated COVID-19 vaccine, patients had a low rate of adverse reactions and demonstrated immunogenicity; the study is ongoing. Efficacy and longer-term adverse event assessment will require phase 3 trials.Trial RegistrationChinese Clinical Trial Registry Identifier: ChiCTR2000031809.

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