Your squad. Your crew. Your pod. Your fam. Your wolfpack.

It's time to add a new one to the list: Your herd.

Why? Because to get this pandemic under control — and to protect our squads, crews, pods and fams — we need what's called "herd immunity." And the COVID-19 vaccine is our best shot (pun totally intended) of getting us there.

"Herd immunity is when a large enough portion of a community is immune to a virus so that the virus can no longer spread easily from person to person," explains Dr. Ashley Drews, medical director of infection prevention and control at Houston Methodist.

According to Dr. Drews, the most realistic way to achieve herd immunity is through wide-scale vaccination. To understand why, look no further than the death toll of this pandemic, as well as the fact that a new variant is on the rise.

"What we've needed since the start of this pandemic is a way to achieve wide-scale immunity without people ever being at risk for developing a severe infection, and COVID-19 vaccines are the best way to achieve this," explains Dr. Drews. "But the existence of a vaccine alone isn't enough to reach herd immunity. It takes people getting vaccinated — many, many people."

How many people need to get vaccinated?

Herd immunity looks different for different viruses. That's because the concept hinges on how easily a particular virus spreads from person to person.

"It's still unclear exactly how many people will need to be vaccinated in order to achieve herd immunity to COVID-19, but experts estimate that it will take at least 70% of the population — with some estimates ranging as high as 90%," says Dr. Drews.

In the U.S., that means at least 248 million people will need to be vaccinated.

"What we need to keep in mind is that some people can't get vaccinated, either due to their age or medical history. So those of us who can get vaccinated need to do our part to protect those who can't," explains Dr. Drews.

Lastly, if you've already had COVID-19, don't assume this means that you don't need to get vaccinated. It's important to know that you can get COVID-19 more than once — meaning vaccination is still important for you, too.

So, even if you're young and healthy and even if you've had COVID-19 and recovered, here's why herd immunity is so necessary.

Herd immunity is powerful — and it takes, well, the herd

To understand herd immunity, let's take a look at our squads, our crew, our pods, our fams — because, whether we've realized it yet or not, these groups have blended together to create one big herd during this pandemic.

Let's say your squad is five of your old college buddies. Three of you are taking the pandemic pretty seriously, but the other two aren't. After what you thought was a safe gathering, three of you end up with COVID-19 — presumably via your friend who's being less safe, but in this fake scenario there's no need to point fingers. You're all young and healthy, and your mild cases aren't fun by any stretch of the imagination, but they're not life-threatening.

But, one of your friends in your squad also has a crew — the three friends he plays golf with on weekends. And before he even realizes he's sick, his crew gets sick, too. Fortunately, only mild cases in the crew, too.

Except, someone in the crew has a wife who is high risk. Unfortunately, she gets COVID-19 — and her case is severe.

The fact is that, right now, your squad isn't just your five friends. Your squad is also the three people in someone else's crew, the 10 people in another person's pod, as well as your family and their own squads, crews and pods. It's also your coworkers, the teachers at your kids' schools and the random people you encounter running errands.

There are no squads, crews and pods during this pandemic, only the herd.

Re-imagine your scenario, but this time with most of your squad vaccinated. Your unvaccinated friend might get COVID-19, but the rest of you are much more likely to be protected. And with only one person ill, the odds of the virus spreading from squad to crew to fam are much lower, too.

Herd immunity won't come easy, though

Like most things pandemic-related, herd immunity comes with a question mark or two.

"In particular, we don't yet know how long vaccine-induced immunity will last. The natural immunity acquired after infection seems to last for several months, and the expectation is that the immunity conferred via vaccination will last even longer. But we don't know exactly how long yet," explains Dr. Drews. "This is one of the major reasons that it will be important to continue wearing a mask after being vaccinated, as well as practicing the other preventive measures we've used to keep our communities safe during this pandemic."

And it's not just questions, there are challenges, too.

"There are logistical hurdles to vaccinating 248+ million people. In addition, many people are still skeptical about these vaccines, and misinformation is adding to this fear," says Dr. Drews.

But, with Delta variant cases on the rise — especially among the unvaccinated — it's time for the entire herd to come together to help to end this pandemic by getting vaccinated.

Remember, to this virus, there are no sqauds, no crews, no pods — only one big herd. And herd immunity, by way of vaccination, is what we need to help keep our squads, crews, pods and fams safe.

Sign up for your COVID-19 vaccine:

All individuals age 5 and older are currently eligible to receive a COVID-19 vaccine in Texas.

• Schedule your vaccine appointment online today

This article was updated on Nov. 11, 2021.