ABSTRACT
Background: COVID-19 pandemic causes severe acute respiratory syndrome and requires rapid action. The development of effective safe vaccines become a global priority for achieving herd immunity. Vaccination is expected to form specific antibodies against the SARS-CoV-2 spike protein which can neutralize the virus, preventing the virus from binding with ACE 2 receptors. Objective: Evaluating and to know if there any differences of kinetics antibody levels from recipient's anti-IgG S-RBD and NAb with complete second dose CoronaVac Vaccine, to determine the antibody response in preventing SARS-CoV-2. Method: A prospective-cohort study using observational analytics was conducted from January-April 2021 at Dr. Soetomo Hospital, Surabaya. A total of 50 subjects are healthcare workers who received two doses of CoronaVac. The IgG S-RBD and NAb levels were measured on Maglumi 800 device (SNIBE, China). Differences in IgG S-RBD and NAb levels before vaccination and after second dose CoronaVac vaccination on 14th day, on 28th day, ware tested using Friedman and Wilcoxon tests. Result: Mean values of IgG S-RBD and NAb have fluctuated. There was a significant difference between IgG S-RBD and NAb levels on day-0 (0.090 vs 18.630; p < 0.001) and day-28 (141.266 vs 116.640; p = 0.037). The median value showed the IgG S-RBD level on day-28 was much better than NAb value (141,266 v 116,640). Conclusion: CoronaVac will form persistent antibodies. Despite antibody development, the acquired humoral immunity decreased at 28 days after full CoronaVac immunization. Kinetics of antibody NAb decreased more rapidly than IgG S-RBD.