Coronavirus News LIVE Updates: US Scientists Developing Nasal Spray to Prevent Covid-19; More Than 2,500 US Virus Deaths in 24 Hours Yahoo India NewsA new study found coronavirus may have been in the US in December. That doesn't mean you'll ever know if you had it then CNNCoronavirus was present in US earlier than initially thought: Study Fox NewsDo SARS-CoV-2 mutations affect its transmissibility?