Herd immunity

Community immunity also known as herd immunity occurs when the community population becomes immune to a disease. Herd immunity happens either by vaccination or due to the increase in the percentage of immune people. With increase in immune people the likelihood of disease spread decreases.

Herd immunity occurs as people become immune to a disease (pandemic or epidemic disease). This can be achieved by either exposure or vaccination. With increase in immunity for a disease, the likelihood of an infected person infecting others decreases. It means the spread of infection will be low and it is because of the herd immunity.

Vaccination: Vaccination is a preventive measure for contagion. With administration of vaccine the immunization will be achieved in the population.

Mass infection: People who survive illness will become immune to future infection. It is like vaccination but could result in illness or death or both.

In past pandemic and epidemic diseases that occurred in world, we have seen emerging herd immunity. During the flu pandemic in 1918-1920, that devastated the world by death of more than a million people, as well as cholera in India for example, the world came together. Scientists found vaccine for such diseases and eventually achieved herd immunity.  Vaccination is critical to eradicate such deadly diseases. In case of polio and smallpox once herd immunity is reached many countries reported successful eradication of both diseases.

Herd immunity can happen when enough a given population recovers from a disease and develops antibodies against future infection.

COVID-19 & Herd immunity:

Is herd immunity can be achieved for Covid-19? According to scientists, relying on community infection to achieve herd immunity has several major issues. Issues such as there is no clear information about the infection and person’s immune to future infection regarding Covid virus. Generally, after an infection with certain type of coronaviruses, getting infected with same virus can cause mild infection in small percent of population. In case of Covid-19, it is yet to determine the protective effect of the antibodies to the virus for future infection.

Further, to achieve long lasting herd immunity for Covid-19, a large number of populations must get infected to reach that threshold. For example, in US alone more than 200 million people that is, 70% of the population must recover from the Covid-19 to put a halt on pandemic. However, when so many people get infected, it could lead to complications and deaths of millions. It also will have huge impact on health care system as it will be overwhelmed.

To achieve herd immunity there is critical need of vaccination.  Till then we all need to focus on slow transmission of Covid-19. To achieve this, it is crucial to protect all individuals who have pre-existing conditions and who are vulnerable to disease. Until we achieve herd immunity we must:

• Avoid large gathering and events
• Must wear masks when in public
• Avoid close contacts
• Stay home as much as possible. Avoid unnecessary travel or outing
• Wash hands often with soap and water for minimum 20 seconds.
• Use hand sanitizer when it is necessary
• Cover mouth and nose using elbow while sneezing and coughing.
• Avoid frequent touching of nose, face, eyes and mouth.
• Do not share dishes, bedding, glasses and household items if you are tested positive and sick to Covid-19
• Stay home if you are sick, do not go to school, college or work. Avoid all public transportation.  Call your doctor or health care system to get more information.

References:

https://www.bannerhealth.com/

https://www.historyofvaccines.org/

Image credit: Photo by Ronê Ferreira from Pexels (Free for commercial use)