The following text discusses public health.
Vaccination works through herd immunity: when enough people are vaccinated, disease cannot spread easily even to those who cannot be vaccinated, such as infants or immunocompromised individuals. The threshold for herd immunity varies by disease—measles requires about 95% vaccination, while other diseases need lower rates. Falling below these thresholds allows outbreaks, as seen in recent measles surges in communities with low vaccination rates. Public health officials therefore focus not just on individual protection but on maintaining population-level immunity.
What does the text say about why population-level vaccination matters?
It only protects the individuals who receive vaccines
It protects vulnerable people who cannot be vaccinated themselves
Herd immunity has been proven impossible to achieve
All diseases require exactly the same vaccination rate
Correct Answer: B
Choice B is the correct answer. The text states that with herd immunity, "disease cannot spread easily even to those who cannot be vaccinated, such as infants or immunocompromised individuals."
- Evidence: Protects those who cannot be vaccinated.
- Reasoning: Population immunity extends protection beyond individual vaccination.
- Conclusion: Vulnerable people are protected through community immunity.
Choice A is incorrect because unvaccinated people are also protected. Choice C is incorrect because the text describes measles requiring 95% vaccination, showing it works. Choice D is incorrect because "the threshold...varies by disease."