To analyze the antibody production of unpaid blood donors after COVID-19 vaccination, and provide basis for the blood donation strategy of healthy people, follow-up vaccine research and development, and COVID-19 prevention and treatment. 1) The sera of 553 unpaid blood donors were collected at the 24th, 36th, 48th and 60th weeks after COVID-19 vaccine inoculation, and the specific SARS-CoV-2 neutralizing antibody was detected by competitive ELISA. The absorbance was inversely proportional to the effective activity of anti RBD neutralizing antibody in the samples; 2) Grouping all volunteers by gender and age, t-tests and analysis of variance were used to statistically analyze the differences in antibody inhibition rates between the groups at each time point of serum collection, in order to clarify the trend of neutralizing antibody inhibition rates on viruses. The neutralizing antibody activity produced by unpaid blood donors who received two different vaccines showed the same trend of change, and the neutralizing antibody activity of the two groups of volunteers remained at a certain level 24 weeks after the last vaccination; After 36 weeks of vaccination, the neutralizing antibody activity showed a slow decrease compared to the previous time point; At the 48th week after inoculation, the neutralizing antibody activity surged to its peak. It was explored that the reason was that most unpaid blood donation volunteers were infected with COVID-19 virus due to the changes in the prevention and control policies of Chinese Mainland on COVID-19, which was equivalent to an active immune response of the body itself, leading to a rise in the neutralizing antibody activity in the body again, even more than 24 weeks after inoculation, and then gradually declined to the normal level. In addition, there was no statistically significant difference in the inhibition rate produced by volunteers of different genders and vaccinated with different types of vaccines at the same time point; However, there was a statistically significant difference in the virus inhibition rate between volunteers under 30 and over 50 years old at various time points (p<0.01). Within 36 weeks after inoculation of COVID-19 vaccine, neutralizing antibodies can maintain their relative vitality against COVID-19 and have protective power against human body, and are basically not affected by age and gender. Timely vaccination against COVID-19 reduces the risk of SARS-CoV-2 infection. After receiving the COVID-19 vaccine, unpaid blood donors can donate blood at normal intervals according to the guidelines provided by relevant ministries and commissions.

Siyun Xu, Songyan Wu, Yunfeng Pu, Jie Wan. Study on the Change of Neutralizing Antibody in Unpaid Blood Donors after COVID-19 Vaccine Inoculation. Academic Journal of Medicine & Health Sciences (2025), Vol. 6, Issue 6: 72-79. https://doi.org/10.25236/AJMHS.2025.060610.

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