Many U.S. colleges and universities are preparing to reopen for the fall semester, with in-person classes scheduled widely. It is understandable that many students, parents and college officials are on edge.

Science is on their side in a way. COVID-19 seems to be most dangerous for older people with pre-existing medical conditions. Younger people can contract the virus, but many demonstrate few, if any, symptoms. It is unlikely, then, that college campuses will become killing fields.

A wakeup call may be necessary for many younger people, however. They are not safe. Well over 10% of the more than 146,000 Americans killed by COVID-19 were in the 15-24 age group, the Centers for Disease Control and Prevention reports. Being less susceptible to the disease does not mean being safe from it.

Higher education officials also are aware of the danger of hundreds of thousands of students leaving home to return to campus — then going home, possibly carrying the virus with them to infect mom, dad, grandman and grandpa.

So restrictions on attendance, some quite stringent, are being implemented at most campuses. One even plans to require students to submit nasal swabs every other day for the first two weeks after they return to campus. Less frequent testing is mandated after that.

Other colleges and universities have less rigid but still demanding requirements. Some plan to fine students who do not comply.

Whatever the restrictions on students, they simply must be enforced strictly. If that means telling a few students to pack their bags and leave campus, so be it. Reopening our colleges and universitiies cannot be permitted to become a lesson in how to make an already severe epidemic explode.