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Published on March 09, 2021

herd immunity block concept

Why COVID-19 Herd Immunity is Important

Now that COVID-19 vaccinations are widely available to the general public, you’ve no doubt heard the term “herd immunity” thrown around. But what exactly does herd immunity mean?

According to the Centers for Disease Control and Prevention (CDC), herd immunity occurs when enough people become immune to a disease to make its spread unlikely. As a result, the entire community is protected, even those who are not themselves immune. Herd immunity is usually achieved through vaccination, but it can also occur through natural infection.

Think of herd immunity like a wet log in a fire. If the logs hold enough water, the fire won’t start. So, if there’s enough immunity in the population, the “spark” of the fire — the virus — never finds much dry fuel to ignite it.

“Were we to await some sort of COVID-19 herd immunity, it would take several years and cost tremendous amounts of money in terms of care, treatment and recovery. It would also lead to many more deaths,” said David Basel, MD, Vice President of Avera Medical Group Quality.

Avera is recommending that everyone get the COVID-19 vaccine, regardless of whether they have recovered from a previous COVID-19 infection. According to the CDC, there is not enough information currently available to say if or for how long after infection someone is protected from getting COVID-19 again; this is called natural immunity. Early evidence suggests natural immunity from COVID-19 may not last very long, but more studies are needed to better understand this.

Basel stresses that there’s no other way to get to herd immunity, and get past this pandemic, without the vaccine.

“The more people who get the vaccine, the closer we can get to ‘back to normal’ and see reduced hospitalizations and deaths due to this virus,” he said.

While masking and social distancing are important, a large number of people getting vaccinated is the only way this virus will get under control. The more people who get the vaccine, the more lives will be saved.

“Our ultimate goal is to play our part in ending this pandemic by vaccinating as many individuals against COVID-19 as we can,” Basel said.

Achieving Herd Immunity

In South Dakota, 12% of our population has had confirmed or probable cases of COVID-19. The actual number is estimated to be up to 20%, based on the fact that not everyone who has symptoms gets tested and some people are asymptomatic. About 14% of our population has been vaccinated (many of whom were previously infected), so at best, 30% of our population is possibly immune. Reaching “herd immunity” requires that 65-85% of the population be immune, so we are far from that.

The herd immunity rumor comes from the nationwide statistic of an estimated three to five infections that stem from every case of COVID. South Dakota’s replication factor was much lower, estimated at under 2, due to our rural landscape and hopefully some of the mitigation efforts we have advocated.

“We need 70% of the population to get vaccinated to get back to our normal lives,” Basel said. “We can visit grandma again, we can start to travel and all of those things.”

For more information about the COVID-19 vaccine, which is now available for everyone 5 and older, visit Avera's vaccine resources page. It includes information that can help you find a nearby vaccination location.

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