CHICAGO (NewsNation Now) — Many Americans turned to the Centers for Disease Control and Prevention for a source of certainty as the coronavirus spread across the country last year.

At first, there were allegations about political interference from the Trump White House, and now under President Joe Biden, recent policies are leading to backlash and confusion.

In the midst of the unknown, some Americans felt the CDC wasn’t doing enough others believe they were overreaching their power.

Dr. John Brooks, chief medical officer for the CDC COVID-19 emergency response, is at the center of it all.

“I think we’re going to always face scrutiny. It’s very difficult to please everyone, and we work for the entire nation,” Brooks said. “We work for every citizen, and we’re trying to protect the whole public health, and it’s always going to be controversial.”

“It’s hard to know when the right time to begin changing things is. It’s easy in retrospect to always second guess what would’ve been the right time. But here’s what we know now — we know that vaccination really works,” said Brooks.

During the pandemic, the CDC’s recommended changes for masking, vaccination, and social distancing became a focal point of frustration. Recently, they’ve made a major recommendation allowing fully vaccinated people to go maskless indoors and outdoors.

“Having spent the last year trying to convince people to wear masks, I fully appreciate the hesitancy,” Brooks said. “I want to just reassure people, first of all, that if you are fully vaccinated, the evidence is very clear, you are protected very strongly against this virus.”

Brooks says the CDC’s future is bright.

You can watch the full interview in the player above.