Abstract : Novel coronavirus become an health emergency by causing severe acute respiratory syndrome and organ failure. Diagnosis of Covid made either by direct antigen detection or by indirect by assessing antibody status against the COVID -19. Aim of this study to assess the seroprevalence conversion after COVID vaccination (Covaxin) in health care workers in North India. Tertiary care hospital based prospective cohort study done in 41 Health Care Workers (HCWs), in duration of 6months. The blood samples of HCWs were taken in between 30 -45 days after Covaxin first vaccination, 30-45 days and 60-65 days after the second dose of Covaxin Vaccination of enrolled HCWs. SARS-CoV-2 IgG antibody against Nucleocapsid Protein (NP) antigen of coronavirus in the serum of HCWs is assessed by chemiluminescence (CLIA) based principal. In 41 Health care workers where number of female was 16 and male was 25, which on follow up after 30 -45 days of first dose Covaxin vaccination shows 29.27% seroconversion, while after in between 30-45 days after second dose of Covaxin vaccination seroconversion rate was 80% and in between 60-65 days after second dose of Covaxin vaccination seroconversion rate was 84.61%. Coronavirus diagnosis by direct antigen detection by reverse transcriptase polymerase chain reaction still gold standard for diagnosis but seroprevalence status assessment can be used to estimate prevalence of COVID-19 as well as efficacy of covid vaccination, beside these seroprevalence play an important role in convalescent plasma therapy.