AUTHOR=Choudhary Hari Ram , Parai Debaprasad , Chandra Dash Girish , Kshatri Jaya Singh , Mishra Narayan , Choudhary Prasanta Kumar , Pattnaik Dipti , Panigrahi Kumudini , Behera Susmita , Ranjan Sahoo Nihar , Podder Sreeparna , Mishra Adyasha , Raghav Sunil Kumar , Mishra Sanjeeb Kumar , Pradhan Subrat Kumar , Sahoo Subrat Kumar , Pattnaik Matrujyoti , Rout Usha Kiran , Nanda Rashmi Ranjan , Mondal Nityananda , Kanungo Srikanta , Palo Subrata Kumar , Bhattacharya Debdutta , Pati Sanghamitra 

TITLE=Persistence of Antibodies Against Spike Glycoprotein of SARS-CoV-2 in Healthcare Workers Post Double Dose of BBV-152 and AZD1222 Vaccines

JOURNAL=Frontiers in Medicine

VOLUME=Volume 8 - 2021

YEAR=2021

URL=https://www.frontiersin.org/journals/medicine/articles/10.3389/fmed.2021.778129

DOI=10.3389/fmed.2021.778129

ISSN=2296-858X

ABSTRACT=Purpose: We investigated the persistence of the vaccine-induced IgG antibodies against SARS-CoV-2 among health care workers in Odisha who received complete dose of either Covaxin or Covishield vaccine.
Methods: This 24-week longitudinal cohort study was conducted from January to  July 2021 with participants from six healthcare and research facilities of Odisha to understand the dynamicity of the vaccine-induced IgG antibodies against SARS-CoV-2, after the complete dose of vaccines. 
Results: Serum samples were collected from 614 participants during each follow-up and were tested in two CLIA-based platforms to detect SARS-CoV-2 antibodies both qualitatively and quantitatively. Among these participants, 308 (50.2%) were Covishield recipients and the rest 306 (49.8%) took Covaxin. A total of 81 breakthrough cases were recorded and the rest 533 heath care workers without any history of post-vaccination infection showed significant antibody waning either from T3 (Covaxin recipient) or T4 (Covishield recipient). The production of vaccine-induced IgG antibodies is significantly higher (p<0.001) in Covishield compared to Covaxin. Covishield recipients produced higher median anti-S IgG titre than Covaxin. No statistically significant differences in antibody titres were observed based on age, gender, comorbidities and blood groups.
Conclusion: This six-month follow-up study documents a two-fold and four-fold decrease in spike antibody titre among Covishield and Covaxin recipients, respectively. The clinical implications of antibody waning after vaccination are not well understood. It also highlights the need for further data to understand the longterm persistence of vaccine-induced antibody and threshold antibody titre required for protection against reinfection.