vaccine is to raise an immune response against a virus or a bacterium, the scientists said in the New York Times.Later, when a vaccinated person is exposed to the actual virus or bacterium, the immune system will then block or rapidly control the pathogen so that the person doesn't get sick, according to Barouch.He added that vaccine development for a new pathogen traditionally takes many years or even decades.The process includes small-scale manufacturing, phase 1, phase 2 and phase 3 clinical trials, and then regulatory approval and large-scale manufacturing.For SARS-CoV-2, the goal is to compress these timelines considerably without compromising safety, which is absolutely critical for any vaccine that will be given to large number of.