Delta variant behind over 80% of new COVID-19 cases in US: Anthony Fauci

The director of the US National Institute of Allergy and Infectious Diseases and the chief medical advisor to the president Anthony Fauci has said that the Delta variant of COVID-19 is responsible for more than 80% of new infections in the country.

He noted that the approved COVID-19 vaccines are more than 90% efficient in avoiding hospitalisations and deaths in the US.

Fauci made this statement during a US Senate hearing on Tuesday.

The hearing featured a heated argument between Republican US Senator Rand Paul and Fauci, in which Paul accused Fauci of lying about the National Institutes of Health sponsoring research at the Wuhan Institute of Virology in China.

In the United States, the origins of the novel coronavirus have become a contentious political thing, with Republicans calling for more investigation into whether it was created in a Wuhan, China.

Late in May, Biden directed aides to look into the virus's origins and report back to him within 90 days.

COVID-19-related deaths in the United States have averaged 239 a day over the last week, up roughly 48 percent over the previous week, according to US Centers for Disease Control and Prevention (CDC) Director Rochelle Walensky.