What Is Herd Immunity?

You may have seen the term “herd immunity” in discussions about COVID-19. A simple definition of herd immunity is a form of immunity in which the majority of a population is immune to a disease or condition.

Herd immunity can occur naturally or through vaccines, so it is possible in some cases. Read on to learn more about this type of immunity, including the importance of herd immunity and other ways to reduce disease transmission.

Herd immunity or herd immunity occurs when enough people in a population are immune to a disease. This type of immunity facilitates transmission from one person to another, and the infection practically does not take root.

The percentage of the population that needs immunity to achieve herd immunity varies from disease to disease. For example, herd immunity against measles requires vaccination of about 95% of the population; As for protection against polio, this figure is about 80%.

Many diseases require a certain percentage of the population to spread further. However, if the proportion of the population that is immune to a disease exceeds the proportion of the population that can be infected, transmission of the disease slows.

Herd immunity can be achieved in two ways: through pre-existing conditions or vaccination.

Existing diseases

Your immune system naturally produces antibodies when faced with a disease to fight infection. Once you recover, you will have protective antibodies against the disease.

Vaccines

, on the other hand, train your immune system to produce antibodies so your body can quickly build up protection if you get sick. This is why herd immunity is partly taken into account with COVID, especially since COVID vaccines are already available.

The more people who are vaccinated, the less likely the virus is to reproduce and spread. At some point, a community or "herd" becomes protected even if it has no immunity or there are people who cannot be vaccinated, such as newborns.

Herd immunity is possible. The key to herd immunity is that there are only a few susceptible hosts that will continue transmission even if one person becomes infected. Anyone who has received the vaccine or is already infected cannot become infected or pass on the virus. However, for some diseases and conditions, achieving herd immunity may be difficult or impossible.

For example, the emergence of new variants of SAR-CoV-2, the virus that causes COVID, means it will be difficult to sterilize immunity through infection or vaccination. Immune sterilization means that a person can no longer become infected or infect others.

Vaccines provide good protection against serious diseases, but cannot prevent infections 100%. Herd immunity is sufficient if there is a vaccine that blocks transmission. Without this type of vaccine, the only way to achieve herd immunity in a population is to vaccinate everyone.

There are several ways to slow the transmission of the disease, including

• avoiding contact with sick people.
• When coughing or sneezing, cover your nose and mouth with a tissue or elbow.
• Vaccination
against diseases
• where recommended, available and appropriate;
• Take your medications as prescribed.
• If you must care for or come into contact with a sick person, use appropriate protective measures such as masks.
• Wash your hands with soap and water or use alcohol. - Hand sanitizer based on no soap and water.

Hermoimmunity is the result of immunity to a specific disease. This can be achieved through natural immunity that develops after contracting a disease, or through vaccination.

How much of the population needs to be immune to achieve herd immunity depends on how contagious the disease is. Although herd immunity is not always possible, there are ways to prevent or reduce the transmission of infectious diseases.

How does herd immunity work? [CBC News Explainer]