It's a big kind of warmth.

There isn't an easy formula to get the herd immunity for a real population.

That's Dr. Christopher Murray.

He's director of the Institute for Health, Metrics, and Evaluation at the University of

Washington in Seattle.

I'm sure you've heard his name by now.

You've certainly seen his models.

The White House and just about everyone else as at one point or another, use these models

to try and predict the future.

He's talking about herd immunity.

It's an idea that if enough people become immune to an infectious disease like COVID-19,

either through vaccination or through infection, then that virus is no longer likely to spread

as quickly across entire populations.

Heard immunity does not mean necessarily that the coronavirus gets completely eradicated

or even that everyone would become immune to the virus.

It's important to know that outbreaks can still occur even after herd immunity is reached.

It's this idea that as the virus isn't transmitting as quickly or as efficiently, the

number of people needed for herd immunity goes down.

But if the virus starts to spread more quickly again, then you need a larger percentage of

people immunized to reach herd immunity.

It's a moving target.

But scientists estimate that it's somewhere between 70 and 85%.

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