Many who fear they have the virus have faced one roadblock after another as they try to get tested, according to interviews with dozens of people across the country.

Some have been rejected because they had no symptoms, even though they had been in proximity to someone who tested positive. Others were told no because they had not traveled to a hot spot abroad, even though they had fevers and hacking coughs and lived in cities with growing outbreaks. Still others were told a bitter truth: There simply were not enough tests to go around.

In some parts of the country, demand for the tests is low. Elsewhere efforts are underway to make testing easier. States like Colorado have even instituted drive-through testing to streamline the process.

But even there, demand has far outstripped supply. By 11 a.m. at one drive-through lab in the Denver neighborhood of Lowry on Thursday, a three-hour line of cars had formed. The clinic had to stop allowing more vehicles.