Herd Immunity and COVID-19: When and How Will We Reach Herd Immunity?

VIDEO: Herd Immunity for COVID-19: Why do we need a vaccine?

Many people became familiar with the term “herd immunity” during the COVID-19 pandemic. But what does it mean? Will we achieve it in the U.S.? And if so, when?

Here’s a quick breakdown of what herd immunity is and what it would take to reach herd immunity for COVID.

What is herd immunity?

According to experts, herd immunity is “when a significant portion of a population becomes immune to an infectious disease.” This helps to slow its spread.

Herd immunity can protect people in a community who are not immune to a disease if enough individuals are immune to the infection. This means that if enough people in your community either got COVID and recovered or received a vaccine against it, it could protect the people who are unable to get the vaccine (due to medical conditions, for example). 

Immunity can come from previous infection or vaccination. But experts prefer to achieve herd immunity through vaccination rather than infection. That’s because vaccination helps avoid unnecessary illness and death that can happen with infection.

How is herd immunity achieved?

There are several moving targets that help a community reach herd immunity. And it depends on the specific disease. That’s because not all infectious diseases are equally contagious. For example, measles is highly contagious; around 95% of the population has to be vaccinated against it before herd immunity is reached. 

It’s also different for each community. Vaccination rates vary widely across the country, even within states. That means the percentage for herd immunity against COVID will likely depend on where you live.

And perhaps most importantly, immunity from infection or the vaccine goes down over time. This makes boosters necessary to maintain immunity. But the pace of people receiving boosters has slowed. 

Have we reached herd immunity for COVID? 

For COVID, experts estimate that we would need between 75% to 85% of people to be vaccinated to achieve herd immunity. But the biggest barrier to herd immunity is how often the virus changes (mutates). The response to vaccination is promising. But research is ongoing on how effective current vaccines are in producing lasting immunity.

Vaccines and boosters are critical to reaching herd immunity. But some people are still hesitant to get the COVID vaccine due to misinformation. Even if more people in the U.S. got their shots, there are still many unvaccinated people around the world. As long as the virus circulates, it has the chance to mutate. This makes herd immunity hard to achieve. 

Will life go back to ‘normal’ after herd immunity? 

This virus has spread around the globe. It’s incredibly infectious and continues to change. For these reasons, experts believe it’s unlikely that the virus will be eradicated. Goal posts have shifted from a target herd immunity percentage to “herd resistance.” This means fewer new infections, hospitalizations, and deaths. 

That said, most people are eager to get back to “normal” — whatever that means for them. In the future, “normal” may include changing behaviors in response to rising COVID cases on a local rather than national level. Like “flu season,” communities may have COVID seasons and will need to decide about masks and local gatherings.

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Written by:

Mandy Armitage, MD

Mandy Armitage, MD, has combined her interests in clinical medicine with her passion for education and content development for many years. She served as medical director for the health technology companies HealthLoop (now Get Well) and Doximity.

Edited by:

Karla Robinson, MD

Karla Robinson, MD, is a medical editor for GoodRx. She is a licensed, board-certified family physician with almost 20 years of experience in health through varied clinical, administrative, and educational roles.

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