To eradicate measles the percentage of population to be vaccinated is at least…………%

**Core Concept**
The concept of herd immunity is crucial in controlling and eradicating infectious diseases like measles. Herd immunity is achieved when a sufficient percentage of a population is immunized, thereby protecting those who are not immunized, such as young children or individuals with compromised immune systems.

**Why the Correct Answer is Right**
To eradicate measles, the World Health Organization recommends that at least 93-95% of the population should be vaccinated. This high percentage is necessary to prevent the continuous circulation of the virus in the community and to protect vulnerable individuals. The measles vaccine is highly effective, with a single dose providing approximately 93% protection against the disease. The high percentage required for herd immunity is due to the highly contagious nature of measles, with a basic reproduction number (R0) of around 12-18.

**Why Each Wrong Option is Incorrect**
**Option A:** 50% - This percentage is too low to achieve herd immunity, as it would allow the virus to continue circulating in the population and infecting susceptible individuals.
**Option B:** 80% - While this percentage is higher than 50%, it is still insufficient to eradicate measles, as the virus can continue to spread and infect individuals in the remaining 20% of the population.
**Option C:** 98% - This percentage is higher than the recommended 93-95%, but it is not necessary to achieve herd immunity.

**Clinical Pearl / High-Yield Fact**
A key aspect of vaccine policy is determining the optimal percentage of the population that needs to be immunized to achieve herd immunity. This percentage can vary depending on factors such as the contagiousness of the disease, the effectiveness of the vaccine, and the presence of vulnerable individuals in the population.

**Correct Answer: C. 95%**