The recent viral infection disease pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has resulted in a global public health crisis. Iran, as one of the countries that reported over five million infected cases by September 2021, has been concerned with the urgent development of effective vaccines against SARS-CoV-2. In this paper, we report the results of a study on potency and safety of an inactivated SARS-CoV-2 vaccine candidate (FAKHRAVAC) in a preclinical study so as to confirm its potential for further clinical evaluation. Here, we developed a pilot-scale production of FAKHRAVAC, a purified inactivated SARS-CoV-2 virus vaccine candidate that induces neutralizing antibodies in Balb/c mice, guinea pigs, rabbits, and non-human primates (Rhesus macaques—RM). After obtaining ethical code of IR.IUMS.REC.1399.566, immunizations of animals were conducted by using either of three different vaccine dilutions; High (H): 10 μg/dose, Medium (M): 5 μg/dose, and Low (L): 1 μg/dose, respectively. In the process of screening for viral seeds, viral strains that resulted in the most severe clinical manifestation in patients have been isolated for vaccine development. The viral seed produced the optimal immunity against SARS-CoV-2 virus, which suggests a possible broader neutralizing ability against SARS-CoV-2 strains. The seroconversion rate at the H-, M-, and L-dose groups of all tested animals reached 100% by 28 days after immunization. These data support the eligibility of FAKHRAVAC vaccine candidate for further evaluation in a clinical trial.

Purpose: This study was completed to assess the immunogenicity and safety of the FAKHRAVAC and BBIBP-CorV vaccines as a booster dose in the population with a history of receiving two doses of BBIBP-CorV vaccine. Methods: In this double-blind, parallel clinical trial, we randomly assigned healthy adults with a history of receiving two doses of the BBIBP-CorV vaccine, who then received either the FAKHRAVAC or BBIBP-CorV vaccine as a booster dose. The trial is registered in the Iranian Registry of Clinical Trial document depository (Code: IRCT20210206050259N4). Results: The outcomes that were monitored in this study were serum neutralizing antibody (Nab) activity, immunoglobulin G (IgG) level, local and systemic adverse reactions, serious adverse events, suspected unexpected serious adverse reactions, and medically attended adverse events. After administering vaccines to 435 participants, the most frequent local and systemic adverse reactions were tenderness and nausea in 23.7% and 1.4% of cases, respectively. All adverse events were mild, occurred at a similar incidence in the two groups, and were resolved within a few days. Conclusions: On the 14th day after the booster dose injection, the seroconversion rate (i.e., four-fold increase) of Nabs for seronegative participants were 87% and 84.6% in the FAKHRAVAC^® and BBIBP-CorV groups, respectively. This study shows that the FAKHRAVAC^® vaccine, as a booster dose, has a similar function to the BBIBP-CorV vaccine in terms of increasing the titer of virus-neutralizing antibodies, the amount of specific antibodies, and safety.