California and San Francisco health departments reported the first individual with the Omicron variant of COVID-19 today. The infected person had traveled to South Africa and returned to the United States on November 22, and was fully vaccinated. However, Anthony Fauci, head of the National Institutes of Allergy and Infectious Diseases and President Biden’s top medical advisor on COVID-19, noted in a White House briefing, that the individual is not believed to have received a booster. All close contacts of the individual have been testing negative, and the infected person has had mild symptoms and been in isolation since November 29. Their symptoms are reported to be improving.

The Omicron variant was first reported in southern Africa last week, though it was likely already present in multiple other countries and it’s unclear where it originated. The new variant, which the WHO has declared a “variant of concern” has a high number of mutations that might make it more transmissible, similar to the Delta variant, which accounts for nearly all of the COVID-19 cases in the US currently. Definite knowledge of the transmission of Omicron will take some time to understand, including whether current vaccines are less effective against it. At this time, though, Dr. Fauci recommends everyone who is eligible for a booster shot to receive one, as it will reduce the risk of contracting any COVID-19 variant and reduce severity of breakthrough cases. 

[Related: 3 important questions about the Omicron variant]

To protect against the spread of all variants, it is important to get vaccinated, receive booster shots if eligible, and continue receiving COVID-19 tests when possible. The US has restricted travel from South Africa and seven other countries as of Monday out of an “abundance of caution,” although permanent US residents and citizens can still return to the country. 

Scientists caution that it is not clear if this variant is any more dangerous than other versions of the virus, but it is a new concern that does need to be taken seriously. The World Health Organization has said that the global risk for the spread of Omicron is high, and although many are operating like the world is done with COVID-19, the virus is not done with us.