Answer to Question 1
Answer: Herd immunity occurs when more than 90 of people in a community are fully vaccinated against a disease, leaving that disease with little ability to spread through the population. It is important because it offers protection to people who cannot be vaccinated or who have not been vaccinated yet.
Answer to Question 2
Answer: Seniors and infants are at higher risk, as are young people with asthma and other chronic respiratory problems, impaired immune systems, or who have been exposed to certain chemicals and environmental pollutants.