The city's largest teachers' union and a prominent public health expert are urging Mayor Bill de Blasio to reconsider his plan to suspend in-person learning throughout the entire NYC school system if positive tests for COVID-19 hit 3% citywide.

In July, months before public schools officially reopened for in-person learning after shutting down in March, de Blasio decided that a seven-day rolling average of positive tests above 3% would trigger a system-wide closure of school buildings. All students will shift to remote learning in the interim.

That plan is being put to the test after nine ZIP codes in Brooklyn and Queens reported COVID-19 cases rising above 3%. There are 80 public schools in the impacted neighborhoods, including Borough Park, Gravesend, and Midwood, which are home to predominantly Orthodox Jewish communities. City officials have said the lack of people wearing masks or social distancing in those neighborhoods have contributed to the spikes, particularly in Gravesend.

While de Blasio maintains he will shut down the school system based on the seven-day rolling average, he hasn’t indicated what happens if that average is skewed by a handful of ZIP codes experiencing exceedingly high rates.

”We are not seeing an interconnection to our public school system so we will watch it very carefully, daily, hourly,” he said on Wednesday. ”If at any point, we determine we need to close an individual school, or any number of schools in that area we will but today, based on the facts, it is not warranted. ”

Dr. Irwin Redlener, Professor of Health Policy and Management and Pediatrics at the Columbia University Medical Center, says decisions like these should be made on a case-by-case basis.

"I personally would not want the city to be so frozen in its policies, that it's not able to modify and change as the situations unfold," said Redlener. "The necessity to be flexible is absolutely critical. I know that makes some people uncomfortable that 'you said it was 3%. And now you're backing off?' Yes, we want them to back off...and I'm okay with that."

De Blasio has been criticized in the past for an apparent lack of flexibility in response to real-time changes. Rebecca Katz, a former consultant to the mayor, told Gothamist that de Blasio has an established pattern of “tell, re-tell, double down, and then compromise at the last minute.”

The United Federation of Teachers is urging the mayor to reconsider his original plan and close the 80 schools in the ZIP codes seeing a spike on COVID-19 tests, a decision that’s not quite outlined in the union’s agreement with the DOE, since none of the cases in these ZIP codes are tied to a school.

Redlener said he agreed with de Blasio’s decision to increase testing in public schools without closing them, since there have been no cases so far in any of the 80 schools in the ZIP codes with high COVID numbers.

"I agree with the city's approach here: focus on the schools and the communities where the problem is, and then, let's try to get it under control there,” Redlener said “The problem with that thinking, the caveat, is that it's not like these schools are in a bubble with respect to the rest of the community. They're pretty isolated in many respects, but teachers may come from other parts of the city or staff in which they do and they are still intermingling. So this is not exactly a foolproof policy just to focus on the schools where the problem is.”

The DOE’s COVID-19 response strategy is guided by a variety of actions that range from isolating sick students for 14 days, closing a school for an indeterminate amount of time, and even shutting down the school system if the citywide positive testing percentage hits 3%.

The plan mirrors the back-to-school strategy in the U.K., France, and Germany, where sick students are ordered to isolate for 14 days while also shutting down individual school buildings entirely if two or more cases surface.

What exactly a full shutdown and a subsequent reopening plan entails is still unclear however. De Blasio’s staff and the DOE did not respond to several questions Wednesday seeking details about how long such a closure would last, what metrics would allow for reopening, how much advance warning would schools receive before a shutdown, and whether the school system was prepared to stay completely remote for weeks.

It’s also unclear what role Governor Andrew Cuomo would play in a school shutdown. Earlier this month, Cuomo reiterated on Tuesday that he will not allow schools to stay open if they are not safe.

De Blasio’s spokesperson, Avery Cohen, referred Gothamist to his comments made on Tuesday that the mayor would make decisions “based on our indicators and the data at the direction of our public health experts,” yet offered no further information on how a system-wide shutdown would be implemented.