Vaccination eliminates diseases such as smallpox and polio by:
a. eliminating susceptible hosts
b. curing infected people
c. killing the pathogens that cause smallpox and polio
d. all of the above
The correct answer and explanation is:
The correct answer is: a. eliminating susceptible hosts.
Vaccination works by creating immunity in individuals and communities, which reduces the number of susceptible hosts for the disease-causing pathogen. This leads to the eventual elimination of the disease, as there are fewer people for the pathogen to infect. In the case of diseases like smallpox and polio, vaccines stimulate the immune system to recognize and fight off the virus without causing the disease itself.
When a significant portion of a population is vaccinated, the spread of the disease slows down or stops entirely. This is because vaccinated individuals are less likely to contract the disease, and even if they do, the chances of severe illness are greatly reduced. This creates what is known as “herd immunity,” where the spread of the disease is contained, protecting even those who are unvaccinated or unable to receive the vaccine due to medical reasons.
Vaccination does not directly cure infected people, as option b suggests. Instead, it prevents infection from occurring in the first place. The pathogens themselves are not killed by the vaccine (option c), but the immune response triggered by vaccination effectively neutralizes the virus, preventing it from causing illness. The goal is not to kill the pathogen directly but to prepare the immune system to fight it off if encountered.
Eliminating the disease through vaccination does not mean that the pathogen is eradicated entirely from the world, but that the transmission is so limited within the population that the disease no longer poses a significant threat. Smallpox, for example, was declared eradicated in 1980, and polio is now close to being eradicated, thanks to widespread vaccination efforts.