The mayor of New York City has warned that the city is getting “dangerously close” to a second wave of coronavirus infections, as the United States passed 10 million cases and public health experts warned that the country is entering the pandemic’s worst phase. On the day that Pfizer announced highly promising results of its vaccine trials, states across the midwest were being deluged with new cases. The governor of Utah declared a statewide emergency and issued a mask mandate - after months of resisting the move.