International Journal of Research and Review Vol. 9; Issue: 8; August 2022 Website: www.ijrrjournal.com Original Research Article E-ISSN: 2349-9788; P-ISSN: 2454-2237 International Journal of Research and Review (ijrrjournal.com) 775 Vol. 9; Issue: 8; August 2022 The Relationship Between the Lymphocyte Value and the Neutralizing Antibody Titer Towards SARS-COV-2 in Residents of Internal Medicine Faculty of Medicine Universitas Sumatera Utara Who Had Received Covid-19 Vaccination Giovani Christin Faitino Purba 1 , Dairion Gatot 2 , Heny Syahrini 2 , Andri Mardia 2 1 Departement of Internal Medicine, Faculty of Medicine Universitas Sumatera Utara 2 Division of Hematology-Oncology, Department of Internal Medicine, Universitas Sumatera Utara Corresponding Author: Giovani Christin Faitino Purba DOI: https://doi.org/10.52403/ijrr.20220865 ABSTRACT Background: Corona virus disease-19 (COVID-19) is a respiratory disease caused by SARS-COV-2 virus. COVID-19 vaccines were designed to produce neutralizing antibody towards the spike (S) protein of the SARS- COV-2 virus. The lymphocyte value has been known to influence the effectiveness of the vaccine. This research was conducted to assess the relationship between the lymphocyte value and the neutralizing antibody titer in residents of internal medicine in Faculty of Medicine, Universitas Sumatera Utara, who had received COVID-19 vaccination. Method: This was an observational analytic study with cross-sectional design, conducted since February to May 2022. The research was performed on residents of internal medicine who had received COVID-19 vaccination. The lymphocyte value was based on the complete blood count, while the neutralizing antibody titer was based on the IgG-SARS-COV-2 titer that was measured using chemiluminescent immunoassay. The data was collected and analyzed using SPSS version 26. Results: There were a total of 45 research subjects included in the study. The mean value of lymphocyte was 31.28% with a mean value of absolute lymphocyte count (ALC) of 2437.99. The mean value of IgG-SARS-COV-2 was 13864.44 AU/ml. The correlation test between lymphocyte value and IgG-SARS- COV-2 titer using Spearman correlation showed a p-valued of 0.476. Conclusion: There was no significant relationship found between the lymphocyte value and the neutralizing antibody titer in residents of internal medicine in Faculty of Medicine, Universitas Sumatera Utara who had been vaccinated (p-value 0.476). Keywords: Lymphocyte, Neutralizing antibody, IgG-SARS-COV-2, Internal Medicine Residents INTRODUCTION Corona virus disease-19 (COVID-19) is a respiratory disease caused by the SARS- CoV-2 (severe acute respiratory syndrome- Coronavirus 2) virus. The World Health Organization (WHO) first referred to this disease as Novel Coronavirus-Infected Pneumonia (NCIP) and the virus that caused it was named 2019-nCov (2019 novel coronavirus). In February 2020, WHO officially named this clinical condition as COVID-19 since the outbreak was first discovered in Hubei in December 2019. The COVID-19 disease itself was officially declared a pandemic since March 2020. (Hafeez, 2020) COVID-19 is an infectious disease that causes severe acute respiratory syndrome, followed by a characteristic hyperinflammatory response, vascular