Welcome to Season 4 of Public Health On Call, a podcast from the Johns Hopkins Bloomberg School of Public Health.

I'm Josh Sharfstein, Vice Dean for Public Health Practice and Community Engagement, and a former Commissioner of Health in Baltimore City.

Our goal is to bring

scientific evidence and experience to current topics in public health through engaging interviews

with scientists, community leaders, policy experts, public health officials, clinicians, and more.

If you have ideas or questions for us to cover, please email us at public health question at jh.edu.

That's public health question at jhh.edu for future podcast episodes.

Today, a bonus episode on breaking news, the Omicron variant. I catch up with

virologists Dr. Andrew Pecosh of the Johns Hopkins

Bloomberg School of Public Health. We'll be talking to Dr. Pecosh periodically as new evidence comes in.

Let's listen. Professor Pecosh, thanks so much for joining us on short notice to talk about

Amicron. How did Amicron come to the world's attention?

So a couple things happened the week of Thanksgiving. Early in the week, some sequences of

a virus that came to be known as the Omicron variant were passed around and available on some national

databases. And they were very concerning on a couple of levels.

One is there was a really large amount of mutations in this virus,

much more than we would expect from the normal evolution of this virus.

And importantly, many of those mutations occurred in the spike protein,

the target of the vaccine, and it's the protein that the virus uses to bind and enter cells.

And to summarize quickly, those mutations look like they would allow the virus to escape from vaccine-induced immunity to some degree,

allow the virus to bind more tightly to cells, and allow the virus to enter cells faster.

So on paper, the sequence of the virus looked

...