Unlike the situation in Dallas, the one in New York City worries me because of the higher population density, and that runs the risk of a higher rate of infection even if the Ebola virus doesn’t transmit like the common cold and influenza viruses.
The situation in NYC actually worries me a little bit less than the situation in Dallas (and I say that as a New Yorker). Yes, NYC has much higher population density, and a much more developed public transportation system. BUT, the window for infection was much smaller in Dr. Spencer’s case than it was for Duncan. Spencer first started showing symptoms yesterday, and was transported to the hospital immediately, by people in biohazard gear. By contrast, Duncan was sent home the first time he went to the hospital (already symptomatic), and when he was brought back to the hospital, he was brought back in a regular ambulance, without any extra precautions, and was placed with other patients for several hours (again, without any extra precautions).