You're listening to shortwave from NPR.

Hey, everybody.

Maddie Sifaya here with NPR Science correspondent Joe Palca, Hado.

And hello, Maddie Sifaya, host of Shortwave.

Hey, Palca.

So you're here because this week there's been a big COVID-19 vaccine development.

Pfizer and its partner, Biontech, announced today some promising but preliminary results

is more than 90% effective, a milestone but not yet conclusive.

That's right.

And company executives were pretty darn excited.

I'm a tend to be a hop to list.

I've been in vaccine development for over 35 years and this is extraordinary.

And I think it speaks well not only for the potential of this vaccine but the potentially

other vaccines out there in development for COVID-19.

That was William Grover, senior vice president of Pfizer vaccine clinical research and development.

And the vaccine appears to be working really well.

It was found to be more than 90% effective and it wasn't just Grover who was excited.

I've been speaking with scientists all week who say this is a really positive result, a

better than they dared to hope.

Yeah.

And I mean, I don't know about you but since the news came out this week, a lot of people

have reached out wondering about this vaccine, what this news means for a vaccine to be effective

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