ABSTRACT
Introduction@#Health care workers of First Central Hospital of Mongolia have vaccinated with three different vaccines against SARS-CoV-2. We detected SARS-CoV-2 N and S-RBD antibodies after 30-90 days of second dose of vaccination. @*Method@#Quantitation of antibodies to the spike protein of SARS-CoV-2 was performed for the detection of adaptive immune response in 291 HCWs vaccinated with Covishield, Sinopharm and Pfizer Biontech. Detection and quantitation of SARS-CoV-2 N and S antibodies were performed by the electrochemiluminesce assay Cobas e411, Roche. @*Result@#SARS-CoV-2-S-RBD IgG titer were negative 0%, weak positive 0.4%, positive 17.5%, strong positive 82.1% of 246 HCWs vaccinated with Covishield and were negative 2.8%, weak positive 8.5%, positive 57.1%, strong positive 31.4% of 35 HCWs vaccinated with Sinopharm. </br> In all HCWs vaccinated with Pfizer Biontech SARS-CoV-2-S-RBD IgG titers were strong positive. @*Conclusion@#Humoral immunity was produced in HCWs after two doses of Covishield vaccine 100%, Sinopharm 97.0%, Pfizer Biontech 100% respectively. Antibody titer was higher among younger age workers.