Early trial results of SARS-CoV-2 vaccines: a review

Main Article Content

Cheng En Xi
Peter Anto Johnson
John Christy Johnson
Austin Mardon



Introduction: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) initially emerged in Wuhan, China in December 2019. The virus causes the disease that is termed COVID-19 and has led to a global pandemic. As of October 16, 2020, it has led to more than 39 million cases worldwide and has killed more than 1 million people. Since the posting of the SARS-CoV-2 genome, vaccine development has begun around the world, with Canada placing orders for millions of vaccine doses through advanced purchasing agreements (APA) with major developers. As of July 2020, early human clinical trial results of three vaccine candidates, namely ChAdOx1, Ad5-nCoV, and mRNA-1273, have been published, two of which are included in Canada’s APAs.

Objective: The aim of this review is to examine and summarize early clinical trial results of the three aforementioned COVID-19 vaccine candidates as of July 20th, 2020. The primary focus of this review will be the methods, procedures, results, and discussions of each published study.
Methods: All vaccine candidates undergoing human trials were searched and identified using PubMed through a combination of search terms. Only the most recent human trial report published in peer-reviewed journals between May 15th and July 20th, 2020, was selected for each vaccine candidate.

Results and Conclusion: The review concludes that all three vaccine candidates have demonstrated a strong safety profile, as well as a robust immune response in the participants of their respective trials. All three vaccine candidates have shown strong immunogenicity, in terms of receptor-binding domain-specific antibody response and neutralizing antibody response. No serious adverse effects were observed in the three trials and all local or systemic reactions were self-limiting. Both ChAdOx1 and Ad5- nCoV will be moving on to phase 3 clinical trials, with mRNA-1273 moving on to phase 2 trials, before the end of 2020.