Study also says that this should not be used to argue against their widespread use to prevent people infecting others

Achieving herd immunity with Covid-19 vaccines involves a range of factors, several of which are unknown

The vaccine’s efficacy rate, the highest of any candidate in late-stage clinical trials so far

Says it appeared Biden was prepared to bring in a professional national security team.

The launch was postponed for a day due to forecasts of gusty winds - remnants of Tropical Storm Eta

Trump has declined to concede, instead lodging unsupported charges of election fraud that have gained little traction

Police picked up Arnab Goswami from his Mumbai home early on Wednesday

A recent report declared it the worst in the world

The brazen attack has been claimed by Islamic State

At least 1,000 people have been killed since fighting broke out on September 27 in Nagorno-Karabakh