Our findings are in concordance to several other studies conducted with different vaccines administered globally

Our findings are in concordance to several other studies conducted with different vaccines administered globally. decrease in GMT at 6-month compared to the peak titer period. Decrease in GMT was insignificant (8%) in Covaxin recipients at 6-month despite a lower GMT whatsoever time points vs. Covishield. There was 5.6-fold decrease in seropositivity rate at 6-month with both vaccines. Participants with type 2 diabetes mellitus have a lower seropositivity rate at all the time points. Seropositivity rate was significantly higher with Covishield vs. Covaxin whatsoever time points except at 6-month where Covaxin recipients experienced a higher seropositivity rate but no difference mentioned in propensity-matched analysis. Conclusions There is waning humoral antibody response following two doses of either vaccine at six months. Covishield recipients experienced a higher anti-spike antibody GMT compared with Covaxin at all-time points, however a significant decrease in antibody titers was seen with Covishield but not with Covaxin at CHMFL-ABL/KIT-155 6-weeks. Keywords: Humoral response, Anti-spike antibody, Covishield, Covaxin, SARS-CoV-2, COVID-19 1.?Intro Vaccination against Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) illness causing Coronavirus CHMFL-ABL/KIT-155 disease 2019 (COVID-19) with ChAdOx1-nCOV (Covishield?) and BBV-152 (Covaxin?) in India started from January 16, 2021 following Emergency Use Authorization (EUA) from the Drug Controller General of India. ChAdOx1-nCOV or AZD1222 or Covishield?, acquired from Oxford University or college and AstraZeneca, manufactured by Serum Institute of India, Pune, is a recombinant replication-deficient chimpanzee adenovirus-vectored vaccine encoding SARS-CoV-2 spike antigen produced in genetically altered human being embryonic kidney (HEK) 293?cells. BBV-152 or Covaxin? manufactured by Bharat Biotech, Hyderabad in collaboration with Indian Council of Medical Study, India, is a -propiolactone inactivated whole virion vaccine having all SARS-CoV-2 proteins adjuvanted with imidazoquinoline, a Toll-like receptor 7/8 (TLR 7/8) agonist, to boost the immune response. While each dose (0.5?ml) of Covishield contains 5 x 1010 viral spike particles, each 0.5?ml dose of Covaxin contains 6?g dose of whole virion inactivated corona computer virus protein of strain NIV-2020-770. The exact proportion of spike antigen in Covaxin is not known. Available phase 3 randomized medical tests (RCTs) of both vaccines found them safe and significantly effective [1,2]. However, there is still a paucity of data in the real-world settings as to how much and how long both these novel vaccines can elicit an immune response both at humoral and cellular level. Long-term antibody kinetics after the completion of both doses of Covishield and Covaxin in Indians is definitely even less well known. We have recently reported the CHMFL-ABL/KIT-155 short-term anti-spike antibody humoral response after the 1st and second dose of both vaccines from Cross-sectional Coronavirus Vaccine-induced Antibody Titre (COVAT) study [3]. Here, we statement a longitudinal 6-month follow-up of humoral antibody kinetics from COVAT study after the completion of the second dose. 2.?Methods 2.1. Study design and participants Our report follows the Conditioning the Reporting of Observational Studies in Epidemiology (STROBE) reporting guideline for cross-sectional studies [4]. COVAT study was a pan-India, cross-sectional study authorized by the honest committee of Thakershy Charitable Trust, Ahmedabad, Gujarat, India. Informed consent was taken on Google-sheet from all the participants who volunteered to participate in this study. Inclusion and exclusion criteria for this study has already been published earlier [3]. Summarily, all adult health care workers (HCWs) of >18 years of age who completed two dose of either vaccine and Rabbit Polyclonal to EMR3 experienced completed a total of four measured anti-spike antibody titre until 6-month of second dose were included in this analysis. Measurement of anti-spike antibody at four time-points include C a. 1st sample:.