# The Atlantic Daily: How to Better Think About Herd Immunity

“It turns out the number is largely up to us.”

Our staff writer James Hamblin set out to try to understand when we’ll reach herd immunity—the point at which enough of a population has been infected to ward off more major spikes of a disease. “It turns out the number is largely up to us,” he explains.

Here are three big takeaways from his new piece on the subject:

1. Herd immunity is calculated differently for an uncontrolled virus.

In the context of vaccination, herd-immunity thresholds are relatively fixed and predictable. In the context of an ongoing pandemic, thinking of this threshold as some static concept can be dangerously misleading.

2. The threshold could be lower than once imagined.

Based on modeling, one mathematician believes it could be as low as 20 percent. Another thinks “between 35 and 45 percent” would be “a level where spreading drops drastically.”

3. But it depends on us.

The threshold can change based on how a virus spreads. The spread keeps on changing based on how we react to it at every stage, and the effects compound. Small preventive measures have big downstream effects. In other words, the herd in question determines its immunity.

One question, answered: Can I use public transit?

Our staff writer Joe Pinsker asked a few experts, including Elizabeth Carlton, a professor at the Colorado School of Public Health. Here’s what he found:

“I would use public transit if it’s the only available option to get from Point A to Point B,” Carlton said. “If you’re able not to use public transit, you’re in some ways making it safer for those who need to use it.”

The experts agreed that if you do get on a subway or bus, you should wear a mask, distance yourself from others, and use hand sanitizer when you disembark. But driving in a car is safer than public transit when it comes to the risk of exposure.

What to read if … you want practical tips:

What to read if … you’re still trying to understand Roger Stone’s pardon:

Read David Frum’s takeaway: “The amazing thing about the saga is how much of it happened in the full light of day.”

What to read if … you’re looking for a new show:

Expecting Amy is a “gorgeous, occasionally gross, and excruciatingly candid” HBO Max miniseries documenting the comedian Amy Schumer’s complicated pregnancy. Our staff writer Sophie Gilbert, herself pregnant with twins, reviews the show in her final piece before going on parental leave.

## Dear Therapist

Every Monday, Lori Gottlieb answers questions from readers about their problems, big and small. This week, she advises a reader who is struggling to end her affair before moving away with her husband:

I am envisioning my new life, relatively joyless, sexless, lonely, and isolated ... How does one handle heartbreak that is a secret?

Read the rest, and Lori’s response. Write to her anytime at dear.therapist@theatlantic.com.