The schools of more than 90 percent of the world’s enrolled students have closed because of the coronavirus pandemic — and it happened over the space of only a few weeks, a United Nations agency said.

Schools in 188 countries had shuttered by March 4, affecting 91.3 percent of students from the earliest years through college and vocational school, the Paris-based U.N. Educational, Scientific and Cultural Organization, reported.

The total number of students affected was 1,576,021,818 — and it is girls who will suffer the most from the closures, the agency known as UNESCO said.

On Feb. 16, only 0.1 percent of the world’s students had been affected, amounting to a little more than 1 million, with China the only country that had shut down schools nationwide. As the novel coronavirus spread from country to country, continent to continent, governments quickly began to take action, ordering nationwide shutdowns of schools and most other aspects of public life.

The Washington Post reported that more than 1.2 million cases of the coronavirus have been confirmed worldwide, although the number could be significantly higher because of the lack of adequate testing in many countries. The United States has the most reported cases, with at least 333,000 people testing positive for the virus, and 9,516 have died in the country.

According to UNESCO, girls will suffer the most from school closure around the world.

Stefania Giannini, UNESCO’s assistant director general for education, and Anne-Birgitte Albrectsen, chief executive for Plan International, a development and humanitarian organization, wrote that of the students out of school, more than 111 million of them are girls living in the world’s least developed countries, “where getting an education is already a struggle ” for them.

Giannini and Albrectsen continued:

“These are contexts of extreme poverty, economic vulnerability and crisis where gender disparities in education are highest. In Mali, Niger and South Sudan — three countries with some of the lowest enrollment and completion rates for girls — closures have forced over 4 million girls out of school.

“For girls living in refugee camps or who are internally displaced, school closures will be most devastating as they are already at a disadvantage. Refugee girls at secondary level are only half as likely to enroll as their male peers.

“While many girls will continue with their education once the school gates reopen, others will never return to school. Education responses must prioritize the needs of adolescent girls’ at the risk of reversing 20 years of gains made for girls’ education.”

Late in March, UNESCO convened a virtual meeting of education ministers from 11 countries — Costa Rica, Croatia, Egypt, France, Iran, Italy, Japan, Mexico, Nigeria, Peru and Senegal — to discuss efforts to keep education continuing with schools shut, and the challenges ahead.

With the importance of science front and center during the pandemic, the agency hosted a March 30 online meeting of representatives of ministries in charge of science representing 122 countries. The goal: to discuss how to promote international cooperation in science and increased investment related to the science of the coronavirus.

“We all depend on science to survive,” Marcos Pontes, Brazil’s minister of science, technology, innovation and communication, was quoted as saying by UNESCO.