KEY POINTS
  • Dr. Craig Spencer, of New York-Presbyterian/Columbia University Medical Center, told CNBC he hopes Americans remember the severity of New York City's coronavirus outbreak. 
  • "We're hoping that everyone around the country learns the lessons that we unfortunately had to learn the hard way," Spencer said on "Closing Bell."
  • "I'm quite concerned that we had this peak, that we've started to trend down and now we're going right back up again," Spencer said. 

When Dr. Craig Spencer got on the New York City subway Monday morning following an overnight hospital shift, the emergency room doctor said all the people he saw were wearing masks. 

"I think that people here remember how bad it was, really just a month, two months, ago and we don't want to go through that again," Spencer, director of global health in emergency medicine at New York-Presbyterian/Columbia University Medical Center, said Monday on CNBC's "Closing Bell."