Zhao Shanlu, Luo Kaiwei, Guo Yichao, Fang Mingli, Sun Qianlai, Dai Zhihui, Yang Hao, Zhan Zhifei, Hu Shixiong, Chen Tianmu, Li Xiaojun
Hunan Provincial Center for Disease Control and Prevention (Workstation for Emerging Infectious Disease Control and Prevention, Chinese Academy of Medical Sciences), Changsha 410005, China.
School of Public Health, Xiamen University, Xiamen 361102, China.
Trop Med Infect Dis. 2023 Jun 20;8(6):330. doi: 10.3390/tropicalmed8060330.
The Omicron variant is the dominant strain circulating globally, and studies have shown that Omicron cases have milder symptoms than Delta cases. This study aimed to analyze the factors that affect the clinical severity of Omicron and Delta variants, evaluate and compare the effectiveness of COVID-19 vaccines with different technological platforms, and assess the vaccine effectiveness against different variants. We retrospectively collected the basic information of all local COVID-19 cases reported by Hunan Province to the National Notifiable Infectious Disease Reporting System from January 2021 to February 2023, including gender, age, clinical severity, and COVID-19 vaccination history. From 1 January 2021 to 28 February 2023, Hunan Province reported a total of 60,668 local COVID-19 cases, of which, 134 were infected with the Delta variant and 60,534 were infected with the Omicron variant. The results showed that infection with the Omicron variant (adjusted OR (aOR): 0.21, 95% CI: 0.14-0.31), getting vaccinated (booster immunization vs. unvaccinated aOR: 0.30, 95% CI: 0.23-0.39) and being female (aOR: 0.82, 95% CI: 0.79-0.85) were protective factors for pneumonia, while old age (≥60 years vs. <3 years aOR: 4.58, 95% CI: 3.36-6.22) was a risk factor for pneumonia. Being vaccinated (booster immunization vs. unvaccinated aOR: 0.11, 95% CI: 0.09-0.15) and female (aOR: 0.54, 95% CI: 0.50-0.59) were protective factors for severe cases, while older age (≥60 years vs. < 3 years aOR: 4.95, 95% CI: 1.83-13.39) was a risk factor for severe cases. The three types of vaccines had protective effects on both pneumonia and severe cases, and the protective effect on severe cases was better than that on pneumonia. The recombinant subunit vaccine booster immunization had the best protective effect on pneumonia and severe cases, with ORs of 0.29 (95% CI: 0.2-0.44) and 0.06 (95% CI: 0.02-0.17), respectively. The risk of pneumonia from Omicron variant infection was lower than that from Delta. Chinese-produced vaccines had protective effects on both pneumonia and severe cases, with recombinant subunit vaccines having the best protective effect on pneumonia and severe pneumonia cases. Booster immunization should be advocated in COVID-19 pandemic-related control and prevention policies, especially for the elderly, and booster immunization should be accelerated.
奥密克戎变异株是全球流行的主要毒株，研究表明，奥密克戎病例的症状比德尔塔病例更轻。本研究旨在分析影响奥密克戎和德尔塔变异株临床严重程度的因素，评估和比较不同技术平台的新冠疫苗的有效性，并评估针对不同变异株的疫苗效力。我们回顾性收集了2021年1月至2023年2月湖南省向国家法定传染病报告系统报告的所有本地新冠病例的基本信息，包括性别、年龄、临床严重程度和新冠疫苗接种史。2021年1月1日至2023年2月28日，湖南省共报告本地新冠病例60668例，其中134例感染德尔塔变异株，60534例感染奥密克戎变异株。结果显示，感染奥密克戎变异株（调整后的比值比（aOR）：0.21，95%置信区间：0.14 - 0.31）、接种疫苗（加强免疫与未接种疫苗相比，aOR：0.30，95%置信区间：0.23 - 0.39）和女性（aOR：0.82，95%置信区间：0.79 - 0.85）是肺炎的保护因素，而高龄（≥60岁与<3岁相比，aOR：4.58，95%置信区间：3.36 - 6.22）是肺炎的危险因素。接种疫苗（加强免疫与未接种疫苗相比，aOR：0.11，95%置信区间：0.09 - 0.15）和女性（aOR：0.54，95%置信区间：0.50 - 0.59）是重症的保护因素，而高龄（≥60岁与<3岁相比，aOR：4.95，95%置信区间：1.83 - 13.39）是重症的危险因素。三种疫苗对肺炎和重症均有保护作用，对重症的保护作用优于对肺炎的保护作用。重组亚单位疫苗加强免疫对肺炎和重症的保护作用最佳，其比值比分别为0.29（95%置信区间：0.2 - 0.44）和0.06（95%置信区间：0.02 - 0.17）。奥密克戎变异株感染导致肺炎的风险低于德尔塔变异株。国产疫苗对肺炎和重症均有保护作用，重组亚单位疫苗对肺炎和重症肺炎病例的保护作用最佳。在新冠疫情防控政策中应提倡加强免疫，尤其是对老年人，应加快加强免疫。
