The Washington Post reported that a pre-diabetic man, Jesús Díaz, 61, was denied the vaccine after failing to provide a social security number. It said Diaz was among at least 14 people refused a vaccine because of residency or immigration status by the University of Texas Rio Grande Valley.

“I felt so much shame and anger at the same time,” Díaz told the newspaper. “I felt discriminated against, but I didn’t want to keep insisting.

In a statement, the university said: “It has come to our attention that we have made some critical mistakes. Most regrettable among these errors is the improper denial of eligible patients at our vaccination sites.