VACCINE DEVELOPMENT & MODERN APPROACHES FOR COVID 19

Most of the infectious diseases due to pathogens are caused by mucosal tract penetration. Hence, vaccines delivered directly tissues can defend pathogenic infections and provide protection at first site infection. Thus, mucosal, specifically, oral delivery is becoming most ideal mode vaccination. However, have overcome numerous barriers such as extremely low pH stomach, presence proteolytic enzymes bile salts well permeability in intestine. Several formulations based on nanoparticles like liposomes, solid solutions, emulsions, VLPs currently being used prepare stable vaccine formulations. In current days different companies trying develop for COVID 19 also. This review briefly discusses several development criteria their mechanisms various aspects nanoparticles-based design that should be considered improved systemic immune responses. 
 Keywords: Vaccine development, nanoparticles, liposome, VLP, 19, immunity.