The level of Ig anti‐RBD SARS‐CoV‐2 after two doses of CoronaVac vaccine

Abstract

The safety and immunogenicity of the two-dose injections of the CoronaVac vaccine (Sinovac Life Sciences) have been reported in Phase 1 and 2 trials. 1,2 After the approval of CoronaVac by the Indonesian government, the coronavirus disease 2019 (COVID-19) vaccination program was launched in January 2021, with the first administration batch targeted towards healthcare workers. However, published data regarding the humoral immune response after Cor-onaVac vaccination in subjects not included in clinical trials are scarce. Therefore, this report aims to evaluate the effectiveness of two doses of CoronaVac vaccine by investigating the level of total Ig anti-receptor binding domain (RBD) severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This is a retrospective study carried out using nonprobability sampling. Subjects were included based on the fulfillment of the following criteria: (1) healthy volunteers; (2) healthcare workers receiving Cor-onaVac vaccine between January and March 2021; (3) has received two doses of CoronaVac (at a 2-week interval [0 and 14 days], with each dose containing inactivated SARS-CoV-2 virus 3 mcg [600 SU] in 0.5 ml); (4) has had a measurement of the Ig anti-RBD quantified by Elecsys Anti-SARS-CoV-2 S (Roche, cut-off value ≥ 0.8 U/ml) after the second dose of CoronaVac vaccine. The Elecsys Anti-SARS-CoV-2 S serology assay is a quantitative electrochemiluminescence immunoassay (ECLIA) utilizing a recombinant protein representing the RBD of the spike antigen and captures predominantly anti-SARS-CoV-2 IgG. 3,4 This study was approved by the Faculty of Medicine and Health Science, Maulana Malik Ibrahim State Islamic University of Malang ethics committee (Ref. No. 023/EC/KEPK-FKIK/2021), and informed consent was obtained from all subjects.The Ig anti-RBD measurement time was varied, ranging from 7 to 49 days after the second dose of the CoronaVac vaccine. Subjects were hence grouped according to the time of Ig anti-RBD measurement. The Ig anti-RBD level between groups was statistically analyzed either by one-way analysis of variance (ANOVA) or paired/ unpaired t-test using SPSS version 25 with a significance threshold of p < 0.05, and all figures were generated using the Graphpad PRISM.Initially, a total of 131 subjects, consisting of 59 male (45%) and 72 female (55%) healthcare workers (mean age overall, 35.

Anti-SARS-CoV-2 spike receptor binding domain (S-RBD) IgG antibodies following CoronaVac administration: a longitudinal study. Anti-SARS-CoV-2 S-RBD IgG antibodies

“…Reports on antibody titers following CoronaVac administration are still scarce, particularly when it comes to the post-vaccination effectiveness of CoronaVac in the Indonesian population [20]. The efficacy of COVID-19 vaccination, particularly the inactivated vaccine type, is still being studied, particularly in terms of a sufficient antibody titer threshold to stimulate a protective effect.…”