As countries around the world start to reopen their economies and consider how to safely reopen schools amid the coronavirus pandemic, international development experts say they are worried that tens of millions of students in the world’s poorest nations may never go back to class.

Alice Albright, chief executive of the Global Partnership for Education, said that the combination of the coronavirus crisis, economic weakness and unrest in some places will affect millions of young people who are out of school and that many will probably not return because of the costs and family pressures on them to work. Girls, she said, will be the most severely affected.

“Because so many of the children who are out of school are the most marginalized, once they are out of school, they are likely to be out for good,” she said. “It is not easy to revert back.”

The Global Partnership for Education is the only global fund solely dedicated to education in developing countries, with contributions from dozens of countries as well as international organizations, the private sector and philanthropy. It works to strengthen education systems in the world’s 67 poorest countries. Of those countries, 58 have closed schools, affecting 341 million children as of Wednesday.

The partnership has made $250 million in emergency funding available for countries to use on education recovery costs during the coronavirus crisis, but Albright said that is nowhere near enough. Two grants have already been approved — $10 million each for Rwanda and Zambia, and 14 more proposals, totaling $152.4 million, are under review. Meanwhile, 36 additional countries have said they will apply for a coronavirus accelerated grant before the end of May, for a total of $361.6 million (more than the amount allocated).

“It will begin to make a dent in the number of students who are out of school,” she said.

The partnership’s emergency funding can be used to, among other things, ensure that learning continues during the pandemic; pay for radios, textbooks and other equipment; support teachers; and provide services for children with disabilities.

According to UNESCO, as of Thursday there were approximately 1.26 billion students, or 72.4 percent of total enrolled learners around the world, still affected by school closures because of the pandemic, which is down from a month ago, when 90 percent, or 1.57 billion students from pre-primary to tertiary education, were out of school (not including the approximately 250 million children, adolescents and youths who were not in school when the pandemic began).

Albright said the impact of school closures is more intense among adolescent girls from the poorest and most rural households because they are more exposed to domestic violence and sexual harassment, and are more likely to be deprived of basic social, health and educational services than boys. As has happened in earlier school closures caused by pandemics, such as the 2014-16 West African Ebola outbreak, experts expect to see an increase in early pregnancies and marriages because of the coronavirus crisis.

Fears about the fate of millions of children are in line with a report released recently by the Nairobi-based charity Oxfam, which said the economic crisis sparked by the pandemic could see the worldwide poverty rate increase for the first time since 1990, with an estimated 548 million people slipping back into poverty after progress in recent decades. If that were to happen, Reuters reported, it would mean nearly 4 billion people worldwide would be living below the $5.50 a day poverty threshold.

Albright said the hardest-hit regions even before the coronavirus are the African countries of Chad, Burkino Faso and Mali, where increasing regional insecurity adds to the difficulties facing the population.

“You have schools being blown up and used as military bases,” she said, “and you have overlaying that huge pressure due to climate change.”

Another problem facing the poorest countries, she said: The pandemic is likely to last longer there than in the developed world, which will be the first to get treatments and a vaccine.