How can Vaccination be Useful in Epidemic [Coranviruse]

-Epidemics is just a Massive Outbreak of a Disease [Coronavirus] -If a Large Percentage of the Population is Vaccinated then the Pathogen will have Less of a Chance of Reaching someone who is Unvaccinated because it needs a Host to stay Relevant. [Reason why people may be Unvaccinated is because of Issues with Trust or People who are Allergic so More Harm would be Created]