"RNA viruses like the coronavirus can mutate when they replicate, especially when circulating at high rates."

"We are looking at the degree of virulence this (Omicron) strain has, we are seeing if the vaccines with which we immu…"

"We engineered three SARS-CoV-2 viruses containing key spike mutations from the newly emerged United Kingdom (UK) and …"

"Funding from American Rescue Plan will help CDC and Governors monitor, track, and defeat emerging variants that are c…"

"We have no alternative but to impose some fairly heavy and immediate restrictions"

"I look at this through a lens of evolution. Early on in the pandemic, I anticipated this would go at least 18 months.…"

"And so the message remains clear. If you are unvaccinated get vaccinated, and particularly in the arena of omicron if…"

"[other countries had seen omicron’s fast growth, but the U.S. data showed] a remarkable jump in such a short time"

"[it’s unclear how much milder omicron really is compared with other variants]. That’s the big uncertainty now"

"We've seen numbers go up, we've seen hospitalizations in kids go up"