Detection and analysis of antibodies against SARS-CoV-2 in blood donors at different periods in Guangzhou

Abstract

Objective To detect the anti-SARS-CoV-2 antibody levels in blood donors in Guangzhou, so as to provide laboratory data support for the collection and clinical use of convalescent plasma. Methods Anti-SARS-CoV-2 antibodies were measured by ELISA in qualified donors. Among them, 326 donors who gave blood in February 2023 were tested for IgG antibodies, 444 donors were tested for neutralizing antibodies. In July 2023, 398 donors were tested for IgG and IgM. Results 399 of 724 blood samples diluted with normal saline (1∶160) were IgG reactive, with a reactive rate of 55.11%. Chi-square test showed that there was a significant difference in the reactive rate of IgG among samples collected at different times (25.46% in February vs 79.40% in July, χ2=210.74, P<0.01, 95%CI: 7.97, 15.98), but there was no significant difference in the reactive rate between different genders and different age groups. IgM was detected in 5 of 398 blood samples, with a reactive rate of 1.26%. The IgG test results of these five blood donors were all reactive, whereas the nucleic acid test results were negative. Neutralizing antibody was detected in 440 of 444 blood samples, with a reactive rate of 99.10%, and 71.59% of the reactive donors had a neutralizing antibody level of 10 μg/mL or more. Conclusion Blood donors in Guangzhou have a high level of SARS-CoV-2 antibody, which is sufficient to provide convalescent plasma for clinical treatment.

Keywords

• blood donor
• sars-cov-2
• antibody