Infection Prevention and Control Department, Yokohama City University Hospital, Yokohama, Japan; Department of Hematology and Clinical Immunology, Yokohama City University School of Medicine, Yokohama, Japan.
Department of Microbiology, Yokohama City University School of Medicine, Yokohama, Japan.
J Infect Chemother. 2022 Feb;28(2):273-278. doi: 10.1016/j.jiac.2021.11.021. Epub 2021 Nov 29.
Levels of 50% neutralizing titer (NT50) reflect the a vaccine-induced humoral immunity after the vaccination against the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Measurements of NT50 are difficult to implement in large quantities. A high-throughput laboratory test is expected for determining the level of herd immunity against SARS-CoV-2.
We analyzed samples from 168 Japanese healthcare workers who had completed two doses of the BNT162b2 vaccine. We analyzed immunoglobulin G (IgG) index values against spike protein (SP) using automated chemiluminescent enzyme immunoassay system AIA-CL and analyzed the background factors affecting antibody titer. SP IgG index was compared with 50% neutralization titers.
The median SP IgG index values of the subjects (mean age = 43 years; 75% female) were 0.1, 1.35, 60.80, and 97.35 before and at 2, 4, and 6 weeks after the first dose, respectively. At 4 and 6 weeks after the first dose, SP IgG titers were found to have positive correlation with NT50 titer (r = 0.7535 in 4 weeks; r = 0.4376 in 6 weeks). Proportions of the SP IgG index values against the Alpha, Beta, Gamma, and Delta variants compared with the original strain were 2.029, 0.544, 1.017, and 0.6096 respectively. Older age was associated with lower SP IgG titer index 6 weeks after the first dose.
SP IgG index values were rised at 3 weeks after two doses of BNT162b2 vaccination and have positive correlation with NT50. SP IgG index values were lower in the older individuals and against Beta and Delta strain.
50%中和效价（NT50）水平反映了接种严重急性呼吸综合征冠状病毒 2（SARS-CoV-2）疫苗后疫苗诱导的体液免疫。NT50 的测量难以大量进行。人们期望有一种高通量的实验室检测方法来确定针对 SARS-CoV-2 的群体免疫水平。
我们分析了 168 名完成两剂 BNT162b2 疫苗接种的日本医护人员的样本。我们使用自动化化学发光酶免疫分析系统 AIA-CL 分析针对刺突蛋白（SP）的免疫球蛋白 G（IgG）指数值，并分析了影响抗体滴度的背景因素。SP IgG 指数与 50%中和效价进行了比较。
受试者（平均年龄 43 岁；75%为女性）的 SP IgG 指数中位数分别为 0.1、1.35、60.80 和 97.35，分别为首次接种前和首次接种后 2、4 和 6 周。首次接种后 4 和 6 周，SP IgG 滴度与 NT50 滴度呈正相关（4 周时 r=0.7535；6 周时 r=0.4376）。与原始株相比，SP IgG 指数对 Alpha、Beta、Gamma 和 Delta 变异株的比例分别为 2.029、0.544、1.017 和 0.6096。首次接种后 6 周，年龄较大者的 SP IgG 滴度指数较低。
两剂 BNT162b2 接种后 3 周，SP IgG 指数升高，与 NT50 呈正相关。年龄较大者和针对 Beta 和 Delta 株的 SP IgG 指数较低。
