A single event in Boston has been linked to up to 300,000 coronavirus cases across the US and even some in Australia, according to scientists. Biotechnology company Biogen's medical conference was held on February 26 and 27, with contact tracers reporting there were just over 100 cases of COVID-19 from the event up until November 1. However a team of scientists tracking the ongoing spread of the virus say the real figure is between 205,000 and 300,000, with the findings published in the journal Science. The conference marked the beginning of a significant spread throughout Boston, the US and even the rest of the world, with scientists noting linked cases began spreading to other US cities in early March, and even ventured as far as Australia and Slovakia. The first cases of human-to-human transmission in Australia were recorded in early March.