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As I understand it, the idea is that the density of viable hosts for a pathogens is reduced so as to effectively halt infections.
The question is posed because ABC news indicates that nearly 1/3 of the US population would not COVID19 vaccinate. Assuming this is true: what is the likelihood of achieving herd immunity with 2/3 of the population? and why?
Is there a minimum percentage that will produce herd immunity?
Is there a minimum percentage that will produce herd immunity?
The percentage of people who need to have antibodies in order to achieve herd immunity against a particular disease varies with each disease. For example, herd immunity against measles requires about 95% of a population to be vaccinated. The remaining 5% will be protected by the fact that measles will not spread among those who are vaccinated. For polio, the threshold is about 80%.
The estimation of the threshold for COVID-19 herd immunity is 70% according to the Mayo Clinic (mirror):
Even if infection with the COVID-19 virus creates long-lasting immunity, a large number of people would have to become infected to reach the herd immunity threshold. Experts estimate that in the U.S., 70% of the population — more than 200 million people — would have to recover from COVID-19 to halt the epidemic.
