Dr. Anthony Fauci has been leading the fight against the pandemic for the last year now.
During a virtual event, the top U.S. infectious disease expert reflected back on what he has learned.
"And one of the things that this outbreak has taught us (is) that scientific investigation and the collection of data and evidence will almost naturally have you evolve your own stance, opinion, guideline or what have you," Fauci said, "Because when you're dealing with virgin territory, an evolving epidemic in front of you, you have to make adjustments."
Fauci has urged people not to relax on COVID protocols until more people are vaccinated.
He has previously said the country needs about 80% of the population to be vaccinated to reach herd immunity.