The new omicron variant took only a few weeks to live up to dire predictions about how hugely contagious it is. But scientists don't yet know if it causes more severe disease even as the world faces exploding cases just before Christmas.
The Centers for Disease Control and Prevention have said that it is clear that omicron does spread faster compared to past strains of COVID-19. In fact, the agency says anyone who contracts omicron should expect to pass it on to someone else, even if the person infected is vaccinated or doesn't have symptoms.
While early data from South Africa has indicated that omicron isn't as deadly as past strains of COVID-19, the CDC says it's too early to make that determination for the variant's behavior in the U.S.
"More data are needed to know if omicron infections, and especially reinfections and breakthrough infections in people who are fully vaccinated, cause more severe illness or death than infection with other variants," the agency said.
Vaccines do not offer as much protection against omicron as they have against previous versions of the coronavirus, as the CDC says omicron will "likely" cause breakthrough cases.
However, vaccines still help — a lot.
White House medical adviser Dr. Anthony Fauci said last week that vaccines still offer substantial protection against omicron.
"Our booster vaccine regimens work against omicron," Fauci said last Wednesday. "At this point, there is no need for a variant-specific booster. And so the message remains clear. If you're unvaccinated, get vaccinated. And particularly in the arena of omicron, if you're fully vaccinated, get your booster shot."
According to lab tests, while two doses may not be strong enough to prevent infection, a booster shot of either the Pfizer or Moderna vaccine produces virus-fighting antibodies capable of tackling omicron.
The CDC says adults who have not yet gotten a booster shot should do so as soon as possible. Those who got a Johnson & Johnson vaccine should seek a booster two months after their initial dose, and those who got Pfizer or Moderna vaccinations should get a booster six months after their final dose.
In addition to vaccines and boosters, the CDC says masks usage and testing are key ways to fight the spread of the omicron variant.
The agency still recommends that Americans continue to wear masks indoors and in large crowds in areas of substantial or high community transmission. As of Wednesday afternoon, the CDC considered the vast majority of the U.S. to be an area of high community transmission.
While the U.S. is currently experiencing a COVID-19 testing shortage, the CDC says Americans should seek out a test if they think they've been exposed or are experiencing symptoms.
"If your self-test has a positive result, stay home or isolate for 10 days, wear a mask if you have contact with others, and call your healthcare provider," the CDC says on its website.