DNA-based Vaccine(Bionet )

In this trial, we are evaluating the safety and tolerability of a new investigational DNA vaccine to protect against SARS CoV-2 virus, called COVIGEN, that is developed by a company called BioNet-Asia.
A device will be used to inject the vaccine that does not require the use of a needle (needle-free injection made by a company called Pharmajet). For delivery into the skin (intradermally) a device called "Tropis" will be used, and for delivery into the muscle (intramuscularly) a device called "Stratis" will be used.
This is a 2 part study
In Part A vaccine naive participants will be given 2 vaccinations, either two active vaccines or two placebo vaccines on Day 1 and Day 29. COVIGEN C19 vaccine will be used in Part A
In Part B participants who have previously received a 2-dose primary COVID vaccine schedule will be given a booster dose of active vaccine. COVIGEN C20 vaccine will be used in Part B.
Participants in part A and B will be followed up using a combination of on-site and telephone visits for assessment of safety and immunogenicity for 12 months from 1st vaccination.