Kessler is a longtime FDA vet, physician, and lawyer who oversaw the critical agency from 1990 to 1997. But he has his work cut out for him as the push for widespread COVID vaccination brushes up against logistical uncertainty and an unruly rollout that has already frustrated multiple state leaders and public health officials.

Why Kessler for this highly specialized role, technically dubbed the chief science officer for COVID response? A breadth of experience across the medical industry and regulatory agencies. As a former FDA commissioner and medical school dean, Kessler understands the intricacies of how health systems work with the federal government and has a finger on the pulse of public health messaging.

The latter skill will be particularly important in the coming months, as public surveys have shown that a wide swath of Americans do not plan on getting a COVID vaccine.

Pandemic fatigue could also discourage simple safety measures such as wearing face masks and social distancing. And knowledge of existing statutes such as the Defense Production Act (DPA), which can be more broadly deployed to make sure that there are enough syringes and basic medical materials to fuel the immunization campaign, play to Kessler’s strengths. Biden has pledged to use the law in a push to administer 100 million COVID vaccine doses to Americans within his first 100 days in office. Kessler has also spoken out on important issues such as the mental health toll and grief fostered by the pandemic.

From Washington to New York City, leaders have decried the disconnect between the federal government and states, which largely carry the burden for distribution strategies. Oregon Gov. Kate Brown on Friday asserted that states wouldn’t be receiving increased doses this week despite previous projections to the contrary. That’s an issue that Kessler will have to tackle head-on in his new role when the Biden administration takes over.

Oregon health officials who spoke with Fortune pointed to the crux of the problem: building trust, maintaining transparency, and keeping the lines of communication open between the federal government and states while conducting an immunization campaign that’s far more complicated than convincing people to go out and get a flu shot.

“We do expect that our federal partners are going to be transparent with us. When our federal partners announce that we’ll be receiving additional supplies, and that we should expand eligibility, and we take them at their word,” says a spokesperson for the Oregon Health Authority.

“And when those doses aren’t there, and we build plans, and we’ve made announcements to people here, in our state, that they can expect a vaccine—that leaves everyone in a really difficult condition and adds to the confusion,” the person added.

The spokesperson says that while states must manage their plans for administration of the vaccines within their own locales, they still rely on the federal government to have conversations with COVID vaccine manufacturers and help allocate the doses. The partnership doesn’t work if one side breaks down.

The Centers for Disease Control (CDC) estimates that 12.3 million Americans have received at least one shot of the two-shot COVID vaccine regimen.