Anti-SARS-Cov-2 S-RBD IgG Antibodies after COVID-19 Inactivated-Vaccine Administration among Infected and Uninfected Health Care Workers

Abstract

Abstract

The evaluation of anti-spike protein receptor-binding domain (S-RBD) antibodies to post-vaccination individuals provides a useful tool to estimate the protection against Severe Acute Respiratory Syndrome CoronaVirus 2 (SARS-CoV-2) infection. In this study, we analyzed the anti-SARS-CoV-2 R-BD IgG antibody among inactivated Covid-19 vaccine-injected subjects of infected and uninfected health care workers. In this cross-sectional designated study, we evaluated anti S-RBD IgG levels by indirect chemiluminescence immunoassay (CLIA) to 50 vaccinated heatlh care workers (HCWs) of the Port Health Office of Semarang. Antibody levels after positive PCR-test or vaccination were analyzed by analysis of variance (Anova). Anti S-RBD IgG levels were higher in post-vaccination infected subjects than both pre-vaccination infection and healthy ones (1,000 v. 147.6 v. 14.36 AU per ml; p < 0.0001). Majority of the post-vaccination infected subjects (84.2%) pronounced mild symptoms but not hospitalized. A remarkable alteration of anti-S-RBD IgG was observed among post-vaccination infected subjects, supports the possibility of secondary antibody response. Induced memory cells were pronounced by vaccinated subjects. Anti-S-RBD IgG prominently raised among post-vaccination infected subjects. Injection with Covid-19 inactivated vaccine might promote memory cells, the secondary immune system. For a direction, immune boosting using a follow-up vaccination is necessary to stimulate IgG production.