After pre-clinical testing on mice, rabbits and monkeys, Nanocovax vaccine was found to be safe and able to generate a high immune response. Based on that result, the vaccine is authorized to proceed to human clinical trials.
The clinical trial of the Nanocovax vaccine went through three phases to fully and in detail evaluate the safety, immunogenicity, and protective efficacy of the vaccine.
Phase 1 (December 10, 2020 - February 8, 2021) took place at the Military Medical Academy (Hanoi) with the main research objective to evaluate the safety of 3 doses of Nanocovax vaccine candidate (25 mcg). /mL, 50 mcg/mL, and 75 mcg/mL) in 60 healthy adult Vietnamese volunteers aged 18-50 years. The phase of determining the vaccine achieved high safety, no serious adverse events occurred, mainly adverse events were mild (grade 1) and resolved quickly after injection.
Phase 2 (February 26, 2021 - April 8, 2021), the main research objective is to compare the immunogenic response of 3 doses of Nanocovax vaccine candidate to determine the optimal dose of the vaccine. At the Military Medical Academy and the Pasteur Institute in Ho Chi Minh City, a total of 560 subjects participated in the study.
Based on the neutralization reaction to reduce necrosis (PRNT) - the gold standard to evaluate the immunogenicity of vaccines, according to international standards and guidelines: proportion of serum samples that react to PRNT50 for Wuhan strains of 3 groups with doses of 25 mcg/mL, 50 mcg/mL, 75 mcg/mL at day 35 were 65.63%, 76.67%, and 78.13%, respectively. This rate increased at day 42, specifically this rate was 96.87% in the 25mcg dose group; 93.75% in the 50mcg dose group and 100% in the 75mcg dose group. The seroconversion rate reached 99.4%. Meanwhile, the serum samples of the placebo dose group were not able to neutralize live virus.
And when analyzing the effect of the immune response: the placebo group was not immunogenic. Meanwhile, the 3 groups vaccinated with the vaccine all had increased levels of IgG antibodies against Protein S of Sars-COV-2 at the time of D28 and high levels of IgG at the time of D42. The 25 mcg dose group had the highest concentration of IgG D42 antibodies.
Based on the above results, 03 groups of doses of Nanocovax 25mcg, 50mcg, 75mcg were concluded to have high safety and quantification of Anti-S IgG as well as high titers of neutralizing antibodies. The difference between these 3 doses was not statistically significant. Therefore, a dose of Nanocovax 25mcg was chosen to continue the phase 3 study.
Results of phase 1 & phase 2 of Nanocovax vaccine: see more here
