In 1918, it appears that school closure was either imposed too late or not kept in place for a sufficiently long time.

In the 21st Century, thuings are different.  With the substantial number of working parents, school closure creates a significant disruption in people’s lives.  An extended school closure, as they did in 1918, would create serious disruptions in the working population, as people had to care for their kids.  This work disruption would affect the health care industry at a time when all health care workers would be needed to treat the sick.