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Reaching ‘Herd Immunity’


The coronavirus pandemic has wreaked havoc on millions of people, businesses and societies around the world for over a year now, causing global implications and a never-ending feeling of getting back to normal life. In the news and in the epidemiology community, you may have heard the term “herd immunity” and what it means to reach this level of transmission of the virus.

Does reaching the level of herd immunity mean that everyone is safe? Does it mean that things go back to normal? For many, the term herd immunity is tossed around in a positive light, meaning that once it’s reached people won’t have to worry about the virus anymore. However, that’s not exactly the case.

What is Herd Immunity?

Herd immunity, according to the Association for Professionals in Infection Control and Epidemiology (APIC), “… occurs when a high percentage of the community is immune to a disease, making the spread of this disease from person to person unlikely.”

Herd immunity is also commonly known as community immunity, and can be reached two ways: either through vaccination and/or prior illness. Per APIC, once a society reaches herd immunity, even individuals that are not vaccinated have some protection because the disease does not have the ability to vastly spread throughout the community.

While reaching herd immunity sounds great, one of the drawbacks could be that there are large groups of unvaccinated people living close to each other that could face a deadly outbreak if the virus made its way into that community. Therefore, you should educate yourself on vaccines if you are ever in doubt to get one or not. Unfortunately, outbreaks can still happen even with vaccine-preventable diseases. This happens when someone brings the virus or disease (usually from outside the country) and comes into contact with someone that has not been vaccinated. Then, the disease spreads from there, infecting those who are unprotected.

There are, however, some instances where diseases have been completely stamped out from using vaccines in the United States, such as smallpox and polio. According to the APIC, vaccines prevent many dangerous and deadly diseases and people have ultimately reached herd immunity with those particular diseases.

Reaching Herd immunity for COVID-19


The single, most important reason why reaching herd immunity is important, per KidsHealth, is because it protects people who are not immune to a disease. Those people include people that have never had the disease, are not able to get a vaccine and/or cannot become immune because they have a weak immune system.

How quickly a region or community reaches herd immunity depends on the contagiousness of the disease. If there is a disease that spreads more easily, such as the measles, it will require a higher number of people to become immune before reaching herd immunity.

Therefore, per the APIC, reaching herd immunity with COVID-19 will largely depend on how many people develop immunity after becoming infected, how long it will take for the general population to get the vaccine and how many people will choose to get the vaccine.

Typically, herd immunity in the past has been reached when large portions of the population become vaccinated and therefore immune to the disease. According to Sharp, when the majority of people are vaccinated and become immune, those who didn’t will benefit from the limited spread of the disease. Reaching herd immunity can also happen through becoming naturally infected with the virus; however, experts believe that would have to be roughly 70% of the population. And along the way, people could become severely ill and/or die, as well as put a strain on the healthcare system by having crowded hospitals and care facilities. This is why the invention of vaccines has played a key role in stamping out deadly diseases in the past.

History of vaccines

Before the first innovations of vaccines were created in the late 1700’s, researchers believe there is evidence that the Chinese created a smallpox injection for use around 1000 CE (AD). And, according to, it was practiced in Africa and Turkey as well before making its way to Europe and the Americas.

In 1796, Edward Jenner created immunity to smallpox through using cowpox material, which quickly helped the spread of the disease and was eventually eradicated.

In 1885, Louis Pasteur’s rabies vaccine paved the way for yet another successful vaccine with many more to follow in the 1930’s, such as diphtheria, tetanus, anthrax, cholera, plague, typhoid and tuberculosis. By the middle of the 20th century, more discoveries were made when scientists learned how to grow viruses in a laboratory, which eventually led to the invention of the polio vaccine. Researchers also grouped together to tackle childhood diseases such as measles, mumps and rubella.

In recent days, several companies have created COVID-19 vaccines and have effectively distributed it to thousands of people around the world, putting everyone on the fast track towards herd immunity.

Where do we go from here?


Reaching herd immunity – when done safely – is an effective way to fight a virus that has impacted millions of people, as the coronavirus has over the past year.

However, there are still a few factors that remain that leave a timeline for herd immunity up in the air. Those factors, according KidsHealth, include:

  • At this time, we are unsure if or for how long people who have recovered from COVID-19 are protected from getting infected again.
  • The Coronavirus is very contagious and so it’s likely millions would have to get infected to create herd immunity, causing many people to get sick and even produce serious long-term effects of the illness.
  • The coronavirus vaccines are still very new, and even though many states have already planned for widespread vaccinations, it may take as long as up to a year before everyone is properly vaccinated.

In the meantime, CEUfast’s Coronavirus Disease 2019 (COVID-19) Course mentions a couple of key reminders to get us through this pandemic, which include:

  • Avoid close contact with people who are sick
  • Maintain six feet of social distancing when possible
  • Avoid touching your eyes, nose and mouth with unwashed hands
  • Stay home when you are sick
  • Cover your cough or sneeze with a tissue, then be sure to throw the tissue in the trash
  • Clean and disinfect frequently touched objects and surfaces using a regular household cleaning spray or wipe
  • Follow CDC’s recommendations for using a facemask
  • Wash your hands often with soap and water for at least 20 seconds, especially after going to the bathroom, before eating and after blowing your nose, coughing or sneezing

As more people start to grow tired of social distancing and isolation, we may continue to see multiple waves of increased positive cases happen over the next year until more people are vaccinated. So as tempting as your friend’s birthday party may be, it may be in your best interest to wait to attend large gatherings until you or a majority of the people at the party are completely vaccinated. After all, reaching herd immunity with the coronavirus may not be as far away as you think.

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