The US has now surpassed six million cases of Covid-19 - almost a quarter of the world's total, according to data collated by Johns Hopkins University. It said the country added one million new infections in less than a month. More than 183,000 people have now died. In the UK, France and Spain, the infection rate dropped compared with Sunday's figures - but the tallies may be readjusted later on. It comes as children across Europe prepare to return to schools this week. The total number of confirmed cases globally has now surpassed 25 million, with more than 846,000 Covid-19 related deaths. The true number of cases is likely to be significantly higher, because many people who have had the infection but did not show symptoms have not been tested. Meanwhile, the World Health Organization (WHO) has warned that the emergency authorisation of vaccines requires a "great deal of seriousness and reflection". The UN body's chief scientist, Soumya Swaminathan, said every country had the right to approve drugs without full trials, but it was "not something that you do lightly". The WHO says that 33 potential vaccines are currently up for clinical trials, and a further 143 are in pre-clinical evaluation.