What is Herd Immunity and how does it relate to COVID-19?

When it comes to preventing a disease like Covid-19 from further spreading, Herd Immunity is crucial! Herd Immunity is when a large sector of a population becomes immune to a disease, usually through vaccination (through which the body is exposed to the virus and develops antibodies against it through primary response). As a result, this hinders the spread of disease through the community and serves as a layer of protection for all individuals, whether vaccinated or not.

Herd Immunity is extremely beneficial as it helps protect those (pregnant women, newborns, immunocompromised individuals, or lower income individuals) who are unable to take vaccinations, by slowing the spread of disease through the community and petering it out of the population. 

In order for a disease to spread, a specific percentage of the overall community population must be capable of contracting that disease- known as the threshold population.  In the event the amount of individuals in the community which are immune is greater than this threshold, rates of disease spread will decrease- herd immunity threshold.

The threshold varies based on the disease at hand. If the disease is more contagious, the threshold will be higher, if not, the threshold will be lower. A prime example of this is measles, in which nearly 94% of the population must be immune in order to reduce infection rates. It is important to note that even after the vast majority of the population is vaccinated, it is still likely that certain individuals may contract the disease. The instance in which someone is in contact with another person, who recently came back from a foreign country, and has traces of this disease is one manner in which outbreaks can happen. 

Covid-19 is an extremely infectious disease, hence a significant portion of the general population will have to be immune to decrease spreading rates and achieve herd immunity. Some researchers believe that 50-67 percent of the population will need to be immune to this virus (through vaccination) to achieve herd immunity and lower infection rates. Currently there is no vaccine for Covid-19 being distributed to the general public but given the great efforts of numerous companies and foundations it is only a matter of time! 

References:

https://www.mayoclinic.org/diseases-conditions/coronavirus/in-depth/herd-immunity-and-coronavirus/art-20486808

https://www.vaccines.gov/basics/work/protection

Herd immunity

https://www.webmd.com/lung/what-is-herd-immunity#1