"The molecular profile of the mutations suggests that it can be passed on more easily and may partially avoid the protection that vaccines provide," Fauci said, noting that this is not known for certain.
In the United States, citizens are advised not to delay the coronavirus booster vaccine until the massive spread of a new variant of the virus.
"If you have the right ... make a booster now," RIA Novosti quotes the doctor as saying.
Earlier, the media reported that the first case of the spread of the omicron coronavirus strain was recorded in the United States.
Fauci later gave details of the first case of omicron identified in the country.