Previously, the CDC approved boosters for all vaccinated adults, but said priority should go to adults over 50.
On Monday, director Rochelle Walensky strengthened that message, calling on all American adults to get extra shots.
Walensky said boosters are key in light of the newly detected Omicron variant.
In light of global concerns about the Omicron variant of the coronavirus, the Centers for Disease Control and Prevention is recommending that all adults get booster doses of the COVID-19 vaccine, to temporarily supercharge the nation's immunity.
Everyone ages 18 and older should get an additional shot, either six months after their Pfizer or Moderna series or two months after their J&J jab, CDC director Rochelle Walensky said in a statement Monday.
The new recommendation marks a vigilant approach toward the emerging Omicron variant (B.1.1.529), which has been detected in the UK, Belgium, Israel, the Netherlands, Canada, Germany, and more, since it was first identified in South Africa.
"The issue with Omicron is that we're concerned it might be partially immune-evading," Dr. Celine Gounder, an infectious disease specialist and epidemiologist at NYU and Bellevue Hospital told Insider, explaining why she agrees with the change in the CDC guidance, given that Omicron is around.
Though it's unclear yet exactly how much of a threat Omicron poses to vaccinated people, "you can overcome some level of immune evasion with an increase in your antibody levels," Gounder said.
And that's exactly what a booster shot does, it temporarily revs up a person's immune response to the coronavirus, sending their antibody levels soaring to even higher levels than first or second shots. That extra bump might be needed, if it turns out that Omicron is more transmissible or more virulent than other versions of the virus that we've seen before.
Getting as many adults boosted as possible in the US now buys the country more time to develop Omicron-specific vaccines, too, if it's determined those are needed.
Previously, the CDC approved boosters for all vaccinated adults - with the caveat that older folks needed them most. But since the emergence of the Omicron variant, the agency has shifted its approach to recommend boosters for everybody 18 and up.
"I strongly encourage the 47 million adults who are not yet vaccinated to get vaccinated as soon as possible and to vaccinate the children and teens in their families as well because strong immunity will likely prevent serious illness," Walensky said in the statement. "I also want to encourage people to get a COVID-19 test if they are sick. Increased testing will help us identify Omicron quickly."
The director also urged the public to follow proven prevention strategies to stop the spread of COVID-19, like wearing face masks, avoiding crowds, and staying home if you're sick.