EXCLUSIVE: Biden's COVID response chief science officer explains what's next

ABC7 News reporter Kate Larsen sat down for a rare interview, with Dr. David Kessler, who co-chaired the Biden-Harris transitions' COVID-19 Advisory Board and is now chief science officer for the Biden administration's COVID response.

Kate Larsen: "What is it like working with President Biden and Vice President Harris?"

Dr. David Kessler: "It's been as intense as one could imagine. It's been 24/7 ."

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Kessler says President Biden is focused on helping the American people, "how do I get shots in arms? How do I bring this country back? How do I relieve the pain and suffering that everyone has endured? It's just been a true pleasure, a privilege and honor. We have more work to do."

Herd immunity:

Kessler, former dean of UCSF's medical school, says he's not sure herd immunity is on the horizon, in terms of eliminating transmission. "I am concerned this virus is going to be with us for some time."

He's the former dean of UCSF's medical school and weighed in on several prominent UCSF physician's assertions this week that California will reach herd immunity by June 15th - when the state is expected to fully reopen. "I love my colleagues at UCSF, I you know, I admire their scientific acumen, their clinical judgment. But, you know, when it comes to herd immunity and that that term, I think we don't know yet know, at what point we will hit, "herd immunity." I think the models are showing a continued reduction in a number of cases. But if herd immunity means that this virus is going to go away, that we're not going to continue to have a significant number of cases and no deaths. I'm not sure that's in the cards."

Vaccine hesitancy:

Kessler says with vaccines, the U.S. can eliminate the most severe cases and deaths. So he's now focused on overcoming vaccine hesitancy and encouraging all Americans to be a part of the solution.

"We all have our job to do. If you've been vaccinated, right? talk to somebody who's not been vaccinated," said Kessler who added. "We just have to be able to help people overcome those fears. We're very close to being at the end of this tunnel."

From faith leaders and physicians to celebrities - Kessler says everyone has a role. He said hundreds of millions of dollars are being spent on vaccine education and messaging. "I'll recruit anybody who's willing to help talk to somebody who's unvaccinated, celebrity or not, everybody can play their role."

Children and the vaccine:

As a pediatrician and former head of the FDA, Kessler understands both the vaccine authorization process and concerns from parents. It's expected the FDA will authorize the Pfizer vaccine for 12-15-year-olds next week. Kessler has seen some of that data but looks forward to seeing more data for all age groups.

Kate Larsen: "When do you think children under 12, babies and toddlers, could be able to get a vaccine?"

Dr. David Kessler: "I don't think the data yet exists for children under 12. I think we have to be a little more cautious as we get into the younger age groups. You know, younger children are just not a little adult. So we have to be cautious. But the one thing I can say, sitting here tonight, is that we're being very, very, very thorough."

Booster shots:

Kessler says they are collecting data on when vaccines may lose some efficacy, "at six months plus, we are seeing some waning of immune response as you would predict."

Kessler expects decisions about COVID booster shots to come within months. "Those over 70, others who are at high risk, they may need to be boosted first."

Sharing the U.S. vaccine supply:

Kate Larsen: "Do you think the U.S., and will the U.S., share more of its vaccine globally, given the horrific crises in India and South America?

Dr. David Kessler: "Absolutely. I think there is no question that there is a very strong commitment to be able to offer vaccines, not only to American citizens but around the world. I think the U.S. pharmaceutical industry deserves a lot of credit. They worked day and night. I regulated the industry when I was at FDA, I was pretty tough on them. I think they deserve a lot of credit, here for working with us to get safe and effective vaccines, and we have an obligation. This is a question of equity within our country, but it's also about equity throughout the world, we have to get this vaccine to countries throughout the world, and especially those who can't afford it. I lived HIV in the 1990s. We learned how to do this, we have an obligation to get vaccines to the world, not just to the United States."

Kessler says the U.S. is not sitting on a stockpile of vaccines but expects that in the coming months, the U.S. will be capable of shipping more vaccines abroad.