He Tingjuan, Wang Meixia, Mi Hongfei, Xu Liansheng, Lu Wenkui, Ouyang Xue, Guo Zhinan, Su Chenghao
School of Public Health, Xiamen University, Xiamen 361102, China.
Department of Infection Control, Xiamen Clinical Research Center for Cancer Therapy, Xiamen 361015, China.
Vaccines (Basel). 2023 Feb 23;11(3):532. doi: 10.3390/vaccines11030532.
Vaccine effectiveness can measure herd immunity, but the effectiveness of inactivated vaccines in Xiamen remains unclear. Our study was designed to understand the herd immunity of the COVID-19 inactivated vaccine against the SARA-CoV-2 Delta variant in the real world of Xiamen.
We carried out a test-negative case-control study to explore the vaccine's effectiveness. Participants aged over 12 years were recruited. A logistic regression was used to estimate the odds ratio (OR) of the vaccine among cases and controls.
This outbreak began with factory transmission clusters, and spread to families and communities during the incubation period. Sixty percent of cases were confirmed in a quarantine site. A huge mass of confirmed cases (94.49%) was identified within three days, and nearly half of them had a low Ct value. Following an adjustment for age and sex, a single dose of inactivated SARS-CoV-2 vaccine yielded the vaccine effectiveness (VE) of the overall case, of 57.01% (95% CI: -91.4486.39%), the fully VE was 65.72% (95% CI: -48.6988.63%) against COVID-19, 59.45% against moderate COVID-19 and 38.48% against severe COVID-19, respectively. The VE of fully vaccinated individuals was significantly higher in females than in males (73.99% vs. 46.26%). The VE among participants aged 1940 and 4161 years was 78.75% and 66.33%, respectively, which exceeds the WHO's minimal threshold. Nevertheless, the VE in people under 18 and over 60 years was not observed because of the small sample size.
The single-dose vaccine had limited effectiveness in preventing infection of the Delta variant. The two doses of inactivated vaccine could effectively prevent infection, and clinical mild, moderate, and severe illness caused by the SARS-CoV-2 Delta variant in people aged 18-60 years in the real world.
疫苗效力可衡量群体免疫，但厦门地区灭活疫苗的效力尚不清楚。本研究旨在了解新冠灭活疫苗在厦门真实世界中针对新冠病毒德尔塔变异株的群体免疫情况。
我们开展了一项检测阴性病例对照研究以探究疫苗效力。招募了12岁以上的参与者。采用逻辑回归分析来估计病例组和对照组中疫苗的比值比（OR）。
此次疫情始于工厂传播集群，并在潜伏期传播至家庭和社区。60%的病例在隔离点确诊。大量确诊病例（94.49%）在三天内被识别，其中近一半的Ct值较低。在对年龄和性别进行调整后，单剂新冠灭活疫苗对总体病例的疫苗效力（VE）为57.01%（95%CI：-91.4486.39%），全程接种疫苗的VE为65.72%（95%CI：-48.6988.63%），针对新冠病毒感染、中度新冠和重度新冠的VE分别为59.45%和38.48%。全程接种疫苗个体的VE在女性中显著高于男性（73.99%对46.26%）。19至40岁和41至61岁参与者的VE分别为78.75%和66.33%，超过了世界卫生组织的最低阈值。然而，由于样本量小，未观察到小于18岁和大于60岁人群的VE。
单剂疫苗在预防德尔塔变异株感染方面效力有限。两剂灭活疫苗可有效预防现实世界中18至60岁人群感染新冠病毒德尔塔变异株以及由此引起的临床轻症、中症和重症疾病。
