From New York Times, I'm Michael Bavaro. This is Adali.

Today, the companies that make COVID-19 vaccines stand to earn enormous profits from booster shots.

So how exactly will we know when or whether we actually need them?

I spoke with my colleague, Rebecca Roberts.

It's Monday, July 19th.

Rebecca, I want to talk about why it is that we're all suddenly talking about booster shots for the COVID-19 vaccine.

And I suspect that it's in part because of the Delta variant. Is that right?

That's definitely part of it. I think we're always going to be having a conversation right around now about whether booster shots would be needed in large part just because enough time has passed since many people got there for shots.

For some people that's been a few months, but for others, it's been six, seven months at this point.

And so I think there was always going to be a question about how long that protection will last.

That said, I think Delta has accelerated these conversations and given them new urgency.

The Delta variant is now the most dominant strain in the United States.

New infections, hospitalizations, even deaths are increasing when many predicted they would be at all-time lows.

You know, Delta has contributed to cases rising across the United States.

We know from the evidence that Delta is more contagious.

And it's, I think, contributing to a sense of uncertainty and insecurity about how far we've gone in tamping down the pandemic.

The fast-bredding Delta variant is raising new concerns and increasing that push to vaccinate.

Might some of us need a booster for this Delta variant?

We've got plenty of questions about the Delta variant and vaccines.

So how good are the vaccines now? And how long do we expect that to last?

Well, these are great questions on everyone's minds, not just parents.

And that has really risen in the minds of people that have been vaccinated so far.

...