Right now, there's a shortage of testing kits for the virus. When more testing is available, we'll get a better idea of how widespread this virus is. We'll be able to screen communities for both active infection and evidence of past infection.
What are "community spread" cases?
In the United States, we're starting to hear about a few cases of COVID-19 from what's called community spread. That means there is no clear source of infection (such as travel to an affected region, or close contact with a patient). This is not at all surprising, especially since people will likely not have effective immunity to this new type of coronavirus. We should expect the number of these community spread cases to continue to rise.