Coronavirus’ spread in the U.S. may be a question of when, not if
COVID-19 cases due to unknown exposure are already cropping up in countries outside China
![](https://i0.wp.com/www.sciencenews.org/wp-content/uploads/2020/02/022520_ac_coronaspread_feat.jpg?fit=1028%2C579&ssl=1)
Cancelling mass gatherings such as concerts or sporting events is one public health step communities could take in the event of wider spread of the new coronavirus.
simonkr/E+/Getty Images