CDC strengthens booster recommendations as worries mount over omicron variant

Prompted by growing concerns about the omicron variant, the Centers for Disease Control and Prevention said Monday that all American adults “should” get booster doses of the available coronavirus vaccines.

Adults ages 18 and older should get a booster shot when they are six months past the initial immunization with the Pfizer-BioNTech or Moderna vaccines, or two months after the single-shot Johnson & Johnson vaccine, the agency said.

The CDC had previously said that Americans over 50, as well as those ages 18 and older living in long-term care facilities, “should” get booster shots while all other adults “may” decide to do so based on their individual risk.The shift in language signals a growing concern about omicron, despite the limited information available about the variant.

Scientists do not yet know whether vaccines will continue to protect people from omicron. The variant contains many mutations that suggest the shots may be less effective against omicron than against other variants.

Dozens of labs worldwide are now trying to assess exactly how much less effective the vaccines might be. They are not expected to have results for at least two weeks.

“Early data from South Africa suggest increased transmissibility of the omicron variant, and scientists in the United States and around the world are urgently examining vaccine effectiveness related to this variant,” Dr. Rochelle Walensky, director of the CDC, said in a statement.

“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.”

Pfizer-BioNTech and Moderna plan to test whether booster shots of their vaccines will bolster the immune system enough to fend off the new variant. The boosters have been shown to raise antibody levels significantly. Those antibodies may not be able to neutralize omicron entirely, but having more antibodies is generally beneficial, experts have said.

Walensky also urged Americans to get tested for the virus if they develop symptoms, and to practice prevention strategies known to limit transmission of the virus.

In just the week after it was first detected, the omicron variant has been spotted in at least 16 countries. The variant has about 50 mutations, including more than 30 in the spike, a viral protein on its surface that the vaccines train the body to recognize and attack.