Safety and Immunogenicity of a DNA SARS-CoV-2 vaccine (ZyCoV-D): Results of an open-label, non-randomized phase I part of phase I/II clinical study by intradermal route in healthy subjects in India

Background: ZyCoV-D is a DNA vaccine candidate, which comprises a plasmid DNA carrying spike-S gene of SARS-CoV-2 virus along with gene coding for signal peptide. The spike(S) region includes the receptor -bind-ing domain (RBD), which binds to the human angiotensin converting Enzyme (ACE)-2 receptor and mediates the entry of virus inside the cell. Methods: We conducted a single-center, open-label, non-randomized, Phase 1 trial in India between July 2020 and October 2020. Healthy adults aged between 18 and 55 years were sequentially enrolled and allocated to one of four treatment arms in a dose escalation manner. Three doses of vaccine were administered 28 days apart and each subject was followed up for 28 days post third dose to evaluate safety and immunogenicity. Findings: Out of 126 individuals screened for eligibility. Forty-eight subjects (mean age 34.9 years) were enrolled and vaccinated in the Phase 1 study Overall, 12/48 (25%) subjects reported at least one AE (i.e. combined solicited and unsolicited) during the study. There were no deaths or serious adverse events reported in Phase 1 of the study. The proportion of subjects who seroconverted based on IgG titers on day 84 was 4/11 (36.36%), 4/12 (33.33%), 10/10 (100.00%) and 8/10 (80.00%) in the treatment Arm 1 (1 mg: Needle), Arm 2 (1 mg: NFIS), Arm 3 (2 mg: Needle) and Arm 4 (2 mg: NFIS), respectively. Interpretation: ZyCoV-D vaccine is found to be safe, well-tolerated and immunogenic in the Phase 1 trial. Our findings suggest that the DNA vaccine warrants further investigation. Funding: Development of ZyCoV-D was supported by a grant-in-aid from COVID-19 Consortium under National Biopharma Mission, Department of Biotechnology, Government of India, to Cadila Healthcare Ltd. (Grant no. BT/COVID0003/01/20). (c) 2021 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)

Automated summary

The Phase 1 trial of ZyCoV-D DNA vaccine conducted in India showed that the vaccine is safe, well-tolerated, and immunogenic, warranting further investigation.