Know all about COVID-19 and Herd Immunity

You’ve probably heard the phrase “herd immunity” used a lot over the past few years, especially in relation to the COVID-19 pandemic. But what is herd immunity, how do we achieve it, and can it really help us fight COVID-19? Let’s take a look.

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What is herd immunity?

Herd immunity, (also called community immunity, or population immunity) is defined as a kind of indirect protection from some infectious diseases. This kind of protection helps both individuals and large communities.

It is said to occur when a large percentage of people in a community become immune to the disease. This happens either through the natural development of antibodies after being infected with a disease or through vaccination.

When this happens, it is said to reduce the spread of the disease. This is because once most of the population is immunized, they do not spread the disease anymore. When this happens, it stops or slows the spread of disease which protects people who aren’t vaccinated, or who have weak immune systems.

How do we achieve herd immunity?

There are two main ways for any community to achieve herd immunity:

When many people contract the disease and build an immune response to it (natural immunity).
When a significant number of people are vaccinated against the disease, and thus achieve immunity.

However, the WHO notes that it is better to achieve herd immunity through vaccination, “not by allowing a disease to spread through any segment of the population, as this would result in unnecessary cases and deaths.” Unlike this natural immunity, vaccination allows people to develop antibodies to a disease without falling ill. It also allows doctors and scientists to periodically boost this immunity (with vaccine boosters) as required.

However it is achieved, herd immunity depends on how contagious a disease is. Diseases that spread easily, like measles, require a higher number of people to be immune to the illness.

For example, in the case of measles, 95% of the population needs to be immune to the disease for the remaining 5% to be reasonably protected from infection. On the other hand, for polio, about 80% of the population needs to be immune.

Does herd immunity work?

While herd immunity can help stop the spread of many infectious diseases, it does not guarantee any community protection against the disease if vaccinations are not also used. This is because a disease can change and evolve more quickly than people develop immunity. Therefore, for most people, natural herd immunity is not a real alternative to getting vaccinated.

However, when herd immunity is achieved through a combination of vaccinations and natural immunity, it could help prevent widespread disease for some illnesses.

For example, in Norway, communities successfully developed partial herd immunity to the H1N1 virus (which caused the Swine Flu Pandemic) using this mixture of vaccinations and natural immunity.

However, for some diseases which cannot be transmitted from person to person but from environmental causes (such as tetanus), herd immunity doesn’t work. In such cases, if there is a vaccine (like the tetanus vaccine), that is the only protection.

Can we achieve herd immunity for COVID-19?

As we have seen, the only way to achieve herd immunity is either through vaccination or exposing people to a disease. However, since COVID-19 is so deadly, herd immunity should only be achieved through widespread vaccination, not by allowing the spread of a disease that could result in unnecessary illness and death.

Scientists still do not know what percentage of people need to be immune to COVID-19 to achieve herd immunity.

Therefore, the main way to fight the disease, save lives, and achieve immunity is through vaccines. Once the majority of the population is vaccinated (including healthy adults, teens, and older children), they will be less likely to contract the virus and transmit it. This will help to provide herd immunity for those who cannot get the vaccine, or develop a natural immunity to the virus.

Herd immunity refers to when a large percentage of people in a community have become immune to a specific infectious disease that the spread of the disease gets significantly slowed down. This is usually achieved through vaccination and natural immunity.

It can certainly be a great help to prevent widespread disease within a country, such as the COVID-19 pandemic. However, since people’s natural immunity against a disease can change or end very quickly, for most people the best way to achieve proper protection against a disease such as COVID-19 is vaccination.

Frequently Asked Questions

Do vaccines help us achieve herd immunity?

Vaccines work by programming your immune system to recognize and fight the virus before you experience any severe symptoms. Since they protect you from getting the disease, they help to break the chain of transmission. This is the most crucial step in achieving herd immunity.

Can we gain herd immunity for COVID-19 without vaccination?

While it is possible to achieve natural herd immunity for COVID-19 (that is, when you get immune to a disease after contracting it), unfortunately, this would come at a high cost. According to a study from Yale University, without vaccination, at least 70% of a population would need to be infected with COVID-19 to achieve herd immunity, but this would cause millions of additional (and avoidable) deaths.

Why is it important to obtain herd immunity against COVID-19?

Herd immunity can help to slow the spread of an infectious disease like COVID-19. The safest way to achieve it is through vaccination. Herd immunity will help protect vulnerable people in the community, such as those who cannot take the vaccination (for example, due to allergic reactions) or those who have compromised immune systems.

How many people need to be immune against COVID-19 to achieve herd immunity?

Scientists are still learning about COVID-19 and how long the immune response is to vaccines. Until there is a better understanding of COVID-19 immunity, we cannot predict the percentage of people needed to achieve herd immunity. However, it can be seen that the more people who are vaccinated, the better a community’s protection against disease.

But, it should be noted that without vaccinations, it is nearly impossible to know what percentage of a population is immune and how long that this immunity will last for. Therefore, increasing immunity by allowing people within a community to get infected is unlikely.

How long will COVID-19 immunity last?

It is yet unclear how long the immune response will continue in vaccinated individuals, though it is predicted to last at least six months to a year (following this, booster doses might be required). This is why it is important to continue using masks, practice social distancing, and follow other COVID-19 guidelines.

Do we still need to take the vaccine if we have already had COVID?

The natural immunity you build up after recovering from COVID-19 will wane after a while. This is why it is important to get the Covid-19 vaccine even if you have already had the disease, as the vaccine can program your immune system to recognise and fight the disease if you get re-infected.

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