As the Delta variant of the coronavirus sweeps across the United States, a growing number of colleges and universities are requiring proof of Covid-19 vaccination for students to attend in-person classes.

But the mandatory requirement has opened the door for those opposed to getting the vaccine to cheat the system, according to interviews with students, education and law enforcement officials.

Both faculty and students at dozens of schools interviewed by The Associated Press say they are concerned about how easy it is to get fake vaccine cards.

Across the internet, a cottage industry has sprung up to accommodate people who say they won't get vaccinated for either personal or religious reasons.