What is herd immunity and why is it important?

What is herd immunity and why is it important?

• A. Herd immunity refers to immunity in herds of animals only.
• B. Herd immunity means disease is completely eliminated.
• C. When a high proportion of the population is immune, disease transmission is limited, protecting those who are not immune.
• D. Herd immunity occurs only after vaccination campaigns.

Answer: (C)

Herd immunity happens when enough people are immune to a contagious disease that the pathogen has fewer opportunities to spread, so the average number of people an infected person passes the disease to falls below one. That slows or stops transmission and provides indirect protection to those who are not immune or cannot be vaccinated. This is important because it lowers the risk of outbreaks, protects vulnerable individuals (like those who can’t be vaccinated or don’t respond well to vaccines), and helps keep healthcare systems from being overwhelmed. It doesn’t mean the disease is completely eliminated or that outbreaks can never occur; immunity can wane, new susceptible individuals can appear, or the pathogen can evolve. Vaccination campaigns are a common, safer way to achieve herd immunity rather than relying on natural infection.

Herd immunity happens when enough people are immune to a contagious disease that the pathogen has fewer opportunities to spread, so the average number of people an infected person passes the disease to falls below one. That slows or stops transmission and provides indirect protection to those who are not immune or cannot be vaccinated.

This is important because it lowers the risk of outbreaks, protects vulnerable individuals (like those who can’t be vaccinated or don’t respond well to vaccines), and helps keep healthcare systems from being overwhelmed. It doesn’t mean the disease is completely eliminated or that outbreaks can never occur; immunity can wane, new susceptible individuals can appear, or the pathogen can evolve. Vaccination campaigns are a common, safer way to achieve herd immunity rather than relying on natural infection.