Joe Biden, Advisor Anthony Fauci Flag Delta Variant Concerns

US President Joe Biden and the country's top medical expert Anthony Fauci have sounded a warning about the highly infectious Delta variant that was first found in India, and which is now the dominant strain in the United Kingdom. 

The Delta variant now accounts for more than 6 per cent of the cases being sequenced in the U.S., said Anthony Fauci, head of the National Institute of Allergy and Infectious Diseases and an adviser. 

The actual number is likely higher, as the U.S. is running the genetic sequence on a fraction of cases.

It has become the dominant strain in the U.K., accounting for an estimated 60 per cent of new cases. It's now more prevalent than the Alpha strain, formerly called the B.1.1.7 strain, which was first identified in the U.K., and transmission is peaking in people between the ages of 12 and 20, he said in a press briefing.

"In the U.K., the Delta variant is rapidly emerging as the dominant variant ... It is replacing the B.1.1.7," Fauci said. "We cannot let that happen in the United States," he told CNBC. 

President Joe Biden also tweeted saying, "A highly infectious COVID-19 strain - is spreading rapidly among young people between 12 and 20 years old in the U.K."

Folks, the Delta variant — a highly infectious COVID-19 strain — is spreading rapidly among young people between 12 and 20 years old in the U.K. If you're young and haven't gotten your shot yet, it really is time. It's the best way to protect yourself and those you love.

— President Biden (@POTUS) June 8, 2021

Currently, 63 percent of adults have received at least one shot of a coronavirus vaccine. Twelve states have crossed 70 percent and more are expected to get there this week, Biden said.

Just over half of adults have been fully vaccinated, leading to a plunge in the toll from the virus, which has killed nearly 600,000 Americans.

President Joe Biden has set a target of getting at least one vaccine shot into the arms of 70 percent of American adults by July 4 -- the nation's Independence Day.

According to the latest Centers for Disease Control and Prevention data, the current figure stands at 63.7 percent.

The Delta variant was first detected in October and has spread to 62 countries, the World Health Organization said last week.