"A major source is smaller social gatherings, as we head into the holidays knowing that people from different households may be gathering, may be convening, it is so important to stay safe," Chokshi said.
"Avoid those types of smaller social gatherings if at all possible and if you do have to have them make sure you are following the rules around distancing and wearing masks because those have been major contributors to spread," he added.
Earlier Mayor Bill de Blasio echoed Chokshi's guidance, saying "please don’t travel," but if you do, "take every conceivable precaution."