Delta variant 'greatest threat' to US' Covid efforts: Dr Fauci

The highly contagious Delta variant of the coronavirus is the "greatest threat" to America's attempt to eradicate the Covid-19 pandemic, White House chief medical advisor Dr Anthony Fauci has warned. Fauci said the variant, which was first identified in India, now makes up more than 20 per cent of all new cases in the US, a significant increase from nearly 10 per cent two weeks ago.