Millions of students may remain out of school for the rest of the academic year in an effort to stop the spread of a deadly coronavirus that has reached pandemic status around the world, officials in several states are warning.

As of late Sunday, 33 states and the District of Columbia had decided to close public schools, according to a tally maintained by Education Week. When combined with the closure of specific school districts in other states at least 32.5 million public school students attending at least 64,000 schools have seen their education interrupted because of the novel coronavirus that has killed more than 6,000 people worldwide.

With the country facing an unprecedented public health crisis, schools have been ordered closed for days or weeks or even a month.

But officials in several states are now warning the closures could be longer, even through the end of the school year. New York City Mayor Bill de Blasio said on Monday morning that it was even possible that schools would be shut even longer.

De Blasio had resisted closing the city’s schools, which educate 1.1 million students, because school for many children is a safe place on which they depend to eat breakfast and lunch, and because he feared that parents who are critical in the life of the New York, such as health professionals and first responders, would have to stay home with their children. But but he came under enormous public pressure to do so and on Sunday the schools were closed from Monday through at least April 20.

“I would love nothing more than to re-open on April 20, which is right after our spring break,” he said on MSNBC’s “Morning Joe.” “But I fear that this crisis is going to start to crescendo through April, May before it ever gets better. The classic ‘it’s going to get a lot worse before it gets better.’ I think that’s a hard atmosphere to reopen schools in.

"Yet if we are lucky, if all things break in our favor, it’s possible [to reopen on April 20]. But I wanted to get people acclimated to a new reality that this is very well going to take us through the school year and maybe beyond because it’s not just the sheer track of the disease. It’s all the other dislocations we have to deal with.”

On Sunday, Ohio Gov. Mike DeWine (R) and Texas Education Commissioner Mike Morath said students in their states may not return to school for the rest of the academic year. There are more than 5.4 million public school students in Texas, and about 1.7 million in Ohio.

On CNN’s “State of the Union” on Sunday morning, DeWine said: “We’ve informed the superintendents why we’ve closed schools for three weeks and … the odds are this is going to go on a lot longer, and it would not surprise me at all if schools did not open again this year.”

Morath held phone calls with superintendents and legislators Sunday and told them “large numbers of kids” in schools where there is significant spread of the novel coronavirus, which causes the disease covid-19, could be kept out of school for the rest of the academic year, the Houston Chronicle reported.

The latest guidance on school closures from the Centers for Disease Control and Prevention was not explicit in its recommendations. It said the available evidence from other countries is those places that did close schools, such as Hong Kong, “have not had more success in reducing spread than those that did not,” such as Singapore.

It also said “available modeling” indicates early closures of a few days or two to four weeks “do not impact” the spread of the virus or hospitalizations but may be useful if many students and staff are absent, or to clean buildings and try to trace networks of people who may have been infected.

“There may be some impact” from school closures of eight to 20 weeks, the CDC said, but that modeling shows that other efforts, such as hand-washing and home isolation, “have more impact on both spread of disease and health care measures.”

Meanwhile, state education officials are grappling with a range of issues, such as how to keep students learning while at home and how to feed students who ordinarily depend on schools to provide them with breakfast and lunch. Other issues include what to do about scheduled standardized testing, which occurs in most states every spring as accountability measures for schools.

In Washington state, Gov. Jay Inslee (D) canceled all state standardized assessments for the remainder of the 2020 school year. In guidance for schools provided by the state, it says at one point when discussing graduating seniors, “[a]ssuming school districts reopen later this spring,” suggesting the Inslee administration is not certain that will happen.

In Illinois, where schools will be closed from March 17 to at least March 30, education officials alerted the public Sunday night that they had no plans to require the days to be made up. The Illinois State Board of Education said in a tweet that it had hosted six virtual town halls with superintendents and other educational leaders and relayed this information: “All of the days during this initial closure March 17-30 will be considered Act of God Days and will not be made up.”

The “Act of God Days” reference refers to a policy that means schools were closed for a condition beyond the control of the district that poses a hazard to the school communities, and that school personnel will be paid through the closure.