As campuses across the country struggle to carry on amid illnesses and outbreaks, a determined minority are beating the pandemic — at least for the moment — by holding infections to a minimum and allowing students to continue living in dorms and attend face-to-face classes.

Being located in small towns, having minimal Greek life and aggressively enforcing social-distancing measures all help in suppressing the contagion, experts say. But one major thread connects the most successful campuses: testing. Extensively.

For months, public health experts have been eagerly watching the companies developing spit tests for the coronavirus that could be used at home, producing results in a matter of minutes.