What is Herd Immunity and How Do Vaccines Help Achieve It?

With COVID-19 continuing to spread, you might feel like this pandemic is never going to end. Stopping a pandemic requires us to use all the available resources to protect ourselves - wearing masks in public, using sanitizing products, and promoting social distancing are just a few ways to reduce our chances of being exposed to the virus or spreading it to others. 

Bottles of COVID-19 Vaccines

Authorized Vaccines for COVID-19

There are currently two vaccines authorized and recommended to prevent COVID-19: the Pfizer-BioNTech COVID-19 vaccine and the Moderna COVID-19 vaccine. Both these vaccines can protect people by producing immunity.  

However, a large number of people must be immune to effectively stop the coronavirus. But how is this possible when the virus is practically everywhere? Herd immunity.  

People inside bubble representing herd immunity

Get Shielded with Herd Immunity

What Is Herd Immunity? 

Herd immunity is “when a large portion of a community (the herd) becomes immune to a disease, making the spread of disease from person to person unlikely.” It becomes harder for this virus to spread in a population with immune systems that have learned how to protect the body against infection.   

How Do Vaccines Promote Herd Immunity? 

Vaccines are powerful tools to achieve herd immunity. According to the CDC, “COVID-19 vaccines help our bodies develop immunity to the virus that causes COVID-19 without us having to get the illness.” 

Measles, mumps, polio, and chickenpox are examples of infectious diseases that were once very common but are now rare in the U.S. because vaccines helped to establish herd immunity

A vaccine will teach our immune systems how to fight the virus if it tries to infect our bodies in the future. It creates T-lymphocytes and B-lymphocytes for our bodies to remember how to fight against harmful antigens. When it detects these contagious invaders, it will produce antibodies to attack them before they can get us sick. 

Why Is It Important to Achieve Herd Immunity? 

It’s important because it benefits those who: 

  • Never encountered the disease 
  • Are unable to get the vaccine (due to medical, financial or geographical reasonings) 
  • Have compromised immune systems 

It helps reduce the risk for vulnerable people, like newborns or senior citizens, from contracting the deadly disease. Keep in mind some people may be asymptomatic. They might not even show signs of having COVID-19 and can pass the virus to vulnerable people unintentionally. Basically, if enough people are resistant to the virus, it eventually has nowhere to go.  

In the worst-case scenario, a very large portion of our population would need to get infected before herd immunity could kick in. And, even once herd immunity is achieved, it is still possible to have large outbreaks where vaccination rates are low.  

Our best chance is to not try to completely stop the virus, just slow it down to prevent a high mortality rate. The current natural herd immunity threshold for COVID-19 is around 60 to 75 percent—but this all depends on if variables like social distancing, using sanitizers, washing hands, and wearing face masks remain constant. 

  Needle going into COVID-19 vaccine bottle

When you can get the vaccine, please do

Do You Still Need to Get Vaccinated Even If You Already Had COVID-19? 

Yes. Since COVID-19 is a new virus, expert studies still do not show if or for how long people who have recovered from COVID-19 are protected from getting infected again. The immunity someone gains from having an infection, called “natural immunity,” varies from person to person—but, so far it appears to be rare for someone who has had COVID-19 to get infected again but we do not know how long this immunity will last into the future.

Also, due to false test results (people who have COVID-19 but test negative, and vice versa), it is safer to get vaccinated. It is estimated that the “vast majority of Americans .... are not immune to SARS-CoV-2...studies show that most people—at least two-thirds—do not have antibodies, and therefore do not have immunity, against SARS-CoV-2.” It’s best to be overly precautious for yourself and others around you.   

What Steps Can I Take to Slow the Transmission of COVID-19? 

  • Wear a face mask covering in public. Keep it over your nose and mouth at all times. 
  • Avoid large events and mass gatherings, especially ones held indoors, with poor air circulation. 
  • Stay at least 6 feet away from people to decrease the chance of contracting COVID-19.  
  • Wash your hands often with soap and water for at least 20 seconds, or use an alcohol-based hand sanitizer gel or wipes that contain at least 60% alcohol. 
  • Clean and disinfect high-touch surfaces, such as doorknobs, light switches, electronics, and counters, daily. 

Stay home from work, school, and public areas if you're sick or you have been exposed to someone who has tested positive or has COVID-19. Please contact your doctor if you are having symptoms, get tested, and stay quarantined until you test negative.