Vaccines: How do they work?

We are posting a three-part information related to COVID-19. First is a minireview on how vaccines work and why they are important to safely fight against pathogens. This was posted today.
The second part is on the basics of both innate and acquired immune response. This will be in the form of a minilecture.
These two parts will place you on good grounds to understand the third part which covers the science behind COVID, how does affect us, and how are we fighting back form vaccines to therapeutics to public safety.