2.4. Laboratory Analysis

The SARS-CoV-2 virus RNA was extracted using the magnetic beads method, according to the instructions of the nucleic acid extraction kit (Shanghai Zhijiang Biotechnology Co., Ltd., Shanghai, China) and then tested by RT-PCR following the steps of the kit in a tertiary protection laboratory. The collected blood samples were centrifuged at 3000 rpm for 10 min to isolate serum and stored at 4 °C before future experiments. All the experiments were carried out at the BSL-2 laboratory. We used the magnetism particulate chemistry method luminescence assay (CMIA) to measure SARS-CoV-2 S-specific binding antibodies at baseline seven days before vaccination and on days seven, 14, 21, 28, and 56 after vaccination with aWanTai 2019-nCoV antibody detection kit. The kit adopts a recombinant sample and 2019-nCoV coating antigen to measure the chemical immunofluorescent signal. The results were showed by RLU which were positively relative to the contents of SARS-CoV-2 S-specific binding antibodies in the serum. The luminometer measured the relative luminescence value RLU average of calibrator 1 and calibrator 2 three times, and calculated the cut-off index (COI). When the samples test value < 1.0 (COI), the 2019-nCoV antibody test result was judged to be negative. When the samples test value ≥ 1.0, the 2019-nCoV antibody test result was determined to be positive. We used intracellular cytokine staining, and T-cell responses were measured at baseline and seven days before vaccination and seven, 14, 21, 28, and 56 days after vaccination. In T cells, we achieved a response in CD4, CD8, CD69 and CD25. In CD19 cells, a response in CD69 and CD25 was realized by flow cytometry detection kit (4ABIO Tech. Co. Suzhou, China) of CD3, CD4, CD8, CD25 and CD69 according to the manufacturer’s protocol.