)When most of a population is immune to an infectious disease, this provides indirect protection—or herd immunity (also called herd protection)—to those who are not immune to the disease.
For example, if 80% of a population is immune to a virus, four out of every five people who encounter someone with the disease won’t get sick (and won’t spread the disease any further). In this way, the spread of infectious diseases is kept under control. Depending how contagious an infection is, usually 70% to 90% of a population needs immunity to achieve herd immunity.
This can happen in two ways:
1)Many people contract the disease and in time build up an immune response to it (natural immunity).
2) Many people are vaccinated against the disease to achieve immunity.
There are several reasons why herd immunity isn’t the answer to stopping the spread of the new coronavirus (COVID-19):
1.There isn’t yet a vaccine for SARS-CoV-2. Vaccinations are the safest way to practice herd immunity in a population.
2.The research for antivirals and other medications to treat COVID-19 is ongoing.
3.Scientists don’t know if you can contract SARS-CoV-2 and develop COVID-19 more than once.
4.People who contract SARS-CoV-2 and develop COVID-19 can experience serious side effects. Severe cases can lead to death.
Doctors don’t yet know exactly why some people who contract SARS-CoV-2 develop severe COVID-19, while others do not.
5.Vulnerable members of society, such as older adults and people with some chronic health conditions, could get very sick if they’re exposed to this virus.
6.Otherwise healthy and younger people may become very ill with COVID-19.
7.Hospitals and healthcare systems may be overburdened if many people develop COVID-19 at the same time.
