The scientific truth about herd immunity

Published October 23, 2020


The U.S. Centers for Disease Control and Prevention (CDC) has updated masking guidelines since this was written. Get the latest information.  

The scientific truth about herd immunity

As we enter a crucial stage in the coronavirus pandemic, Nebraska’s hospitals and public health agencies want you to know the truth about herd immunity. You may have read about this concept as a way to get us through this difficult time. It would be disastrous for our country, our health care systems, and for millions of fellow Americans. 

The herd immunity concept assumes that everyone who recovers from COVID-19 is immune from re-infection. That is an assumption that has not been proven. In fact, medical scientists have now reported a number of persons with proven re-infection. With a virus that has existed for less than a year, it is impossible to know whether people can be re-infected on a large scale. 

Let’s look at the numbers:

For herd immunity to take hold, you would need a minimum of 60% of the entire population to be infected. Antibody studies tell us that some small pockets of New York City and Mumbai, India, may have reached 50% infection rates, but cities with major outbreaks have had overall infection rates of less than 25%. Based on CDC testing nationally, we estimate 10% of the U.S. population has experienced COVID-19 coronavirus infection. Given the overall number of confirmed deaths, we can estimate that approximately 0.6% of people with COVID-19 will perish as a result. As of this writing, over 220,000 Americans have already died from COVID-19. So, what would happen if 60% of the population were infected rather than 10%? Here are our estimates for what a "herd immunity" experience in the US would look like:

  • 197 million cases
  • 3.6 million people hospitalized
  • 1.2 million deaths

This is not a solution. The loss of life would be many times more devastating than what we see now. The economic impact would be ruinous for our state and country. If you see statements that claim otherwise, keep in mind there has not been a single scientifically verified study anywhere in the world that shows unchecked herd immunity as a solution. 

What is the solution? As scientists around the world work tirelessly toward a vaccine, we must follow what we know works to stop the spread.

We agree with state leaders who encourage you to avoid the three Cs:

  • Crowded places: Avoid gathering in groups where you cannot maintain a minimum of 6 feet of distance from others
  • Close contact: Wear a mask whenever you are within 6 feet of people from outside your household. Masks work – scientific data from around the world continues to show this. In areas with mask mandates, the primary driver of COVID cases is people who spent significant time without their masks on in places like bars and restaurants
  • Confined spaces: Avoid enclosed spaces with poor ventilation. We know how the virus spreads. When people are physically separated from others by 6 feet or more in well-ventilated areas, they are much less likely to become infected.

We do not have to choose between the total shutdown of society and letting the virus run unchecked through the population. We can instead rely on science and a spirit of helping each other by protecting each other and getting through this together.

UNMC | Nebraska Medicine | Douglas County Health Department | Children's Hospital & Medical Center | Boystown National Research Hospital | Methodist | Pottawattamie County Public Health | Saunders Medical Center | Memorial Community Hospital & Health System | CHI Health