“However, we are seeing steady increases and that is a concern,” he said. “And another thing that is of great concern is if the new strain gains a foothold here, it can really spread very, very quickly.”
Epidemiologists fear asking for new immediate blocks. Instead, for now, they are calling for targeted measures to try to reduce infection rates, as an impetus for further testing in the most affected and most vulnerable CEPs.
Conversely, parts of the city with the lowest rates of the virus – rich ZIP codes in Manhattan and Brooklyn – tend to have the highest rates of testing, city data show. That should change, said Frieden, with more tests appearing in the most affected areas.
Patrick Gallahue, a spokesman for the city’s health department, said the city was already focusing its testing resources on the most affected areas. Additional restrictions on business or meetings, he said, would have to be enacted by the state.
But to reverse the course in New York City before a vaccine goes into effect, more drastic measures, such as a blockade, are likely to be needed, several experts said.
City officials need state permission before instituting any citywide closings, except schools. Mr. Cuomo suggested that schools close only if the infection rate inside school buildings was higher than that of the community. In the middle of the week, the positive test rate in schools across the city was much lower, at 0.49%.
Dr. Nash said that other red lines and parameters must be established to guide shutdown decisions, such as one around mortality: How many deaths per day will we accept before we block? He also called for more attention to local conditions, such as rates of virus in neighborhoods with overburdened intensive care units, and the speed of transmission of the virus, a measure known as R0, which is not regularly reported by the state. State officials say they track these numbers internally.