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Herd immunity and what it means during the COVID-19 pandemic

 IMF World Economy
Posted at 4:00 AM, Feb 05, 2021
and last updated 2021-02-05 11:09:48-05

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Since the start of this pandemic, there has been a lot of talk about "herd immunity" and the best ways to achieve it. Vaccinations help us get there, but before we talk about achieving herd immunity, we first must understand what herd immunity is.

"Herd immunity is the idea that one individual may not have gotten protected from an infection or may not have had that infection, but the more people in their herd or group who have protection to that infection, the less likely they are to get it, " explains Amber D'Souza, an epidemiology professor at Johns Hopkins University. "So when a majority of people have protection from an infection, the herd is less likely to transmit that infection."

It sounds simple enough, but getting to herd immunity in our current pandemic is anything but easy.

"Herd immunity is based on how contagious a virus is," explains Dr. Piyush Gupta with Blue Cross Blue Shield of Arizona. "For example, there are certain diseases where you need about 90% of the community protected against a virus. Measles for example is highly, highly contagious....there are other viruses where you may only need 80%. Currently, I believe the coronavirus is 70-75%, given how transmissible or contagious the virus is."

That's the goal of the vaccination sites popping up across the state and country -- to reach herd immunity through protecting people who haven't already had COVID-19. Experts say it would save more lives than simply letting COVID-19 spread like wildfire within the population.

But Dr. Gupta warns that herd immunity isn't a "cure all." COVID-19 could still spread in our community, but not nearly as easily as it once did.

"[It] won't stop it, but it will slow it down significantly. There will still be a risk that people who don't have that aren't immune to the virus and they could still get it. But the risk is much lower because it's less prevalent in our communities."

The interesting thing about herd immunity is that like the name suggests, it doesn't just protect you; it protects all of us. The less likely you are to get sick, the less likely you are to spread that disease to someone else.