Fauci urges Americans to get Covid booster as US surpasses 50m positive cases

Leading infectious diseases official warns Omicron variant appears to be able to evade' protection of two initial doses

The US government's leading infectious diseases official, Anthony Fauci, has stepped up calls for Americans to get a Covid-19 booster shot, as the US hit the grim milestone of 50m positive cases - by far the highest of any nation in the world.

According to the latest numbers from Johns Hopkins university the US now has some 50,025,005 cases of the virus. In terms of deaths, the figures show that the US is also now approaching 800,000 lives lost to coronavirus since the start of the pandemic.