When will schools reopen? It depends on where you live, who’s in charge and whether they believe Anthony Fauci.

When will schools reopen in the United States?

The unsatisfying answer is that it all depends - on where you live, who is in charge and how much the decision-makers respect the opinion of infectious-disease specialist Anthony S. Fauci and the other scientists leading the fight to stem the spread of the coronavirus.

Officials in 21 states have ordered or recommended that all schools - many of which have been closed for at least a month already - stay shuttered throughout the end of the 2019-2020 school year, according to a tally kept by Education Week. Two more states are closed "until further notice," while other states have varying opening dates, some of which have been pushed well into May. Tens of millions of students are at home, attempting distance learning with varying degrees of success.

President Trump has said repeatedly he wants to open the country for business as soon as possible, often mentioning May 1 as a goal. Yet epidemiologists are warning that the coronavirus, which has already killed more than 22,000 people in the United States, will be a threat to public health for many months. And Fauci, who is the director of the National Institute of Allergy and Infectious Diseases and who has become the medical community's leading spokesman on the pandemic, has suggested that schools may be able to open in the fall if current efforts to "flatten the curve" are successful. He was nothing if not indefinite.

"You know, it is unpredictable, but you can get a feel for it if we start talking about the things where the curve goes down," Fauci said at a recent White House briefing. "How we respond and what kind of a rebound we see or don't see, I think is going to have a lot of influence probably more immediately on things like summer camps than it does in the fall." (Trump on Sunday night retweeted a call for the firing of Fauci, who has said lives could have been saved if the response in the United States had been faster.)

Michael T. Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota, wasn't convinced in March that shutting down schools en masse was the best approach to containing the virus. On Monday, he said opening schools will have to be smartly managed and that the situation "requires a national policy" to decide when and how to open schools.

But Trump has given no indication he is going to do that, and state leaders don't always see eye to eye on the subject.

For example, Washington state Superintendent of Public Instruction Chris Reykdal said last week at a news conference that students will continue with online learning from home for the rest of the school year - and, if necessary, into the fall. The state, he said, will be ready for a return to the classroom in the fall "if we get the right science in our favor."

In Maryland, State Superintendent of Schools Karen Salmon told a group of state lawmakers recently that she is stepping up efforts to improve distance-learning delivery in the state in case a flare-up of the coronavirus in the fall or winter keeps students at home again. Officially, Maryland's schools are closed only until April 24, though that is likely to be extended as some districts, including Montgomery County, the largest in the state, struggle to provide full distance-learning programs to all students.

In Florida, Gov. Ron DeSantis (R), who was slow to take statewide steps to curb the virus, said late last week that he wants to see students back in their classes as soon as possible and that there could be value in allowing students in some districts without serious outbreaks to return even for two weeks in the 2019-2020 school year.

Though scientists have warned about selective reopenings of public life because of the likelihood of re-contamination, DeSantis said, "it may be that not every county is going to be treated the same in all this."

He added, falsely: "This particular pandemic is one where I don't think nationwide there's been a single fatality under 25. For whatever reason, it just doesn't seem to threaten, you know, kids."

New York has seen a public spat about the reopening of schools - exactly when and who gets to decide - between Gov. Andrew Cuomo and New York Mayor Bill de Blasio, both Democrats who don't get along.

De Blasio, who initially wanted to keep schools open in March to give students from poor families a safe place to go and to eat, said last week that the city's public school district, the largest in the country, would stay closed for the rest of the 2020-2021 academic year.

But Cuomo said over this past weekend that it was his call as governor - not the mayor's decision - and that he didn't know yet when schools should open.

Cuomo said that de Blasio was only expressing his "opinion" and that he, the governor, would coordinate with neighboring states in deciding when schools should open.

Meanwhile, there remains debate about whether it's even effective to close schools. From a new peer-reviewed article in the medical journal the Lancet:

Data from the SARS outbreak in mainland China, Hong Kong, and Singapore suggest that school closures did not contribute to the control of the epidemic. Modelling studies of SARS produced conflicting results. Recent modelling studies of COVID-19 predict that school closures alone would prevent only 2-4% of deaths, much less than other social distancing interventions. Policy makers need to be aware of the equivocal evidence when considering school closures for COVID-19, and that combinations of social distancing measures should be considered. Other less disruptive social distancing interventions in schools require further consideration if restrictive social distancing policies are implemented for long periods.

Aaron E. Carroll, professor of pediatrics and associate dean for research mentoring at Indiana University School of Medicine, said comparing SARS, or severe acute respiratory syndrome, which appeared in China in the early 2000s, to covid-19 is questionable, as SARS was a very different disease that was not as contagious as covid-19 and did not have asymptomatic spread. Closing schools now makes sense.

"I absolutely do not think it was the wrong thing to do," he said.

As for when schools can start to reopen, he said that can start to happen only when public health officials can safely identify people who are infected with covid-19, isolate them, and treat them and all of their contacts.

When will that happen? He, like everybody else, doesn’t yet know.