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

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 your chances of being exposed to the virus or spreading it to others. 

Authorized Vaccines for the Virus

And now we have three vaccines authorized here in the United States -- the Pfizer-BioNTech, Moderna, and Johnson & Johnson vaccines -- with more still being worked on. These vaccines can protect people by producing immunity.  

However, a large number of people must be immune to effectively protect us. And how do we accomplish this? 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, “Vaccines help our bodies develop immunity to the virus ... 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 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 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. And, unfortunately, quite a few states are already cutting back on restrictions or removing them completely way before we have reached a high vaccination rate.

Get Vaccinated as Soon as You Are Allowed

Do You Still Need to Get Vaccinated Even If You Have already been Infected?

Yes. Due to the newness of the virus, expert studies still do not show if or for how long people who have recovered 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 the virus to get infected again. However, we do not know how long this immunity will last into the future.

Also, due to the possibility of false test results, it is safer to get vaccinated. It is estimated that the “vast majority of Americans .... are not immune to the virus ... studies show that most people—at least two-thirds—do not have antibodies, and therefore do not have immunity, against the newest virus.” It’s best to be overly precautious for yourself and others around you.   

What Steps Can I Take to Slow the Transmission? 

• 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 the virus.  
• Wash your hands often with soap and water for at least 20 seconds, or use an alcohol-based hand sanitizer or wipes.
• 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 is currently ill. Please contact your doctor if you are having symptoms, get tested, and stay quarantined until you test negative.