Serological follow-up of anti-SARS-CoV-2 antibodies in blood donors after COVID-19 vaccine booster dose and breakthrough infections in Fuzhou / 中国输血杂志

ABSTRACT

【Objective】 To analyze the dynamics of specific SARS-CoV-2 IgG antibodies in blood donors in Fuzhou area after receiving booster doses of inactivated COVID-19 vaccine and breakthrough infections, and to provide evidence for the timing of the collection of specific immune plasma or convalescent plasma and the subsequent vaccine doses. 【Methods】 A total of 109 volunteers who received the first booster dose of inactivated COVID-19 vaccine and 102 volunteers who experienced breakthrough infections were recruited at Fujian Blood Center from October to November 2021. Blood samples were collected at eight time points 14 (11, 20) days before the booster dose (Time0), 14 (10, 23) days after the booster dose (Time1), 53 (45.5, 61) days after the booster dose (Time2), 88 (78, 101.5) days after the booster dose (Time3), 124 (112.5, 138.5) days after the booster dose (Time4), 158 (146, 174) days after the booster dose (Time5), 194 (179.5, 214) days after the booster dose (Time6) and within one month after the breakthrough infection (Time7). Serum SARS-CoV-2 IgG antibodies were detected using a chemiluminescence immunoassay. The dynamics of antibody levels were analyzed and the effects of age, gender, weight, BMI, blood type and smoking on antibody levels were also analyzed. 【Results】 The positive rate of SARS-CoV-2 IgG antibodies was 53.2% (58/109) at Time0, 100% (109/109) at Time1, and 95.4% (104/109) at Time6. The antibody levels were significantly higher at Time1 and Time6 than at Time0 (P0.05). The IgG antibody level at Time7 was 2.07 times than that at Time1 (P0.05). The IgG antibody level in breakthrough infection group was significantly higher than that in non-breakthrough infection group (P<0.001). 【Conclusion】 Booster doses of inactivated COVID-19 vaccine and breakthrough infections can stimulate stronger immune responses in the body. It is recommended to collect specific immune plasma or convalescent plasma within one month after breakthrough infections or booster doses of COVID-19 vaccine for special purposes. The timing of subsequent vaccine doses should be based on the dynamics of antibody levels. It is necessary to continuously monitor antibody levels to provide evidence for subsequent vaccine doses.