U.S. infectious disease expert Anthony Fauci, who is President Joe Biden’s top medical adviser, believes that boosters for fully vaccinated individuals provide "the strongest available protection" from Covid, according to a White House readout of Biden’s meeting with Covid response team on the omicron variant on Sunday, November 26.

"Fauci informed the President that while it will take approximately two more weeks to have more definitive information on the transmissibility, severity, and other characteristics of the variant, he continues to believe that existing vaccines are likely to provide a degree of protection against severe cases of Covid," the White House said.

"The Covid Response Team’s immediate recommendation to all vaccinated adults is to get a booster shot as soon as possible."

All adults are eligible for a booster if they were vaccinated six months ago or more with Pfizer or Moderna, or two months ago or more with Johnson & Johnson.

Biden has restricted U.S. travel links starting Monday, November 29 with eight African countries including South Africa, where omicron was first identified.