What is herd

This is known as the herd immunity threshold. What percentage of a community needs to be immune in order to achieve herd immunity? It varies from disease to disease. The more contagious a disease is, the greater the proportion of the population that needs to be immune to the disease to stop its spread.

For example, the measles is a highly contagious illness. Herd immunity can be reached when enough people in the population have recovered from a disease and have developed protective antibodies against future infection.

However, there are some major problems with relying on community infection to create herd immunity to the virus that causes COVID :. Herd immunity also can be reached when enough people have been vaccinated against a disease and have developed protective antibodies against future infection. Unlike the natural infection method, vaccines create immunity without causing illness or resulting complications. Using the concept of herd immunity, vaccines have successfully controlled contagious diseases such as smallpox, polio, diphtheria, rubella and many others.

Herd immunity makes it possible to protect the population from a disease, including those who can't be vaccinated, such as newborns or those who have compromised immune systems. The U. For example:. The number of fully vaccinated adults continues to rise. In addition, more than 31 million people in the U. However, if you are in an area with a high number of new COVID cases in the last week, the CDC recommends wearing a mask indoors in public and outdoors in crowded areas or when you are in close contact with unvaccinated people.

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Measles was declared eliminated in Yet in , there were 1, cases reported in the U. Outbreaks of vaccine-preventable diseases still occur when too few individuals in a population are vaccinated.

Outbreaks often begin with an imported case someone who was travelling outside the U. These infected people then expose unprotected people to the disease. For example you need two measles, mumps, and rubella MMR injections to be adequately protected. Some people may only receive one and mistakenly believe they are protected. Conflicts of Interest Disclosure Identify all potential conflicts of interest that might be relevant to your comment.

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Limit characters or approximately words. The following information is required and must be completed in order to submit a comment:. Thank You. Your comment submission was successful. Please allow up to 2 business days for review, approval, and posting. Can anybody please name a disease where proper herd immunity with elimination of the disease has been achieved through natural infection?

Except, perhaps, diseases like the plague where the disease killed off the infection reservoirs. Has herd immunity eliminated measles, TB, polio, smallpox? I might be mistaken but I always thought it was vaccination that eliminated smallpox. For a disease like Covid, it could eventually achieve an equilibrium at tremendous cost with few active cases and slower spread but it would always be there waiting to infect those who had been shielding.

Sorry, people knowledgeable about medicine and public health may understand this but politicians and the general public don't. Hence the myths so prevalent In the popular press and social media. Access your subscriptions. Access through your institution. Add or change institution. Free access to newly published articles. Purchase access. Rent article Rent this article from DeepDyve.

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