Can instructors ask a student if they are vaccinated?

It is recommended that instructors/advisers/graduate teaching assistants not ask a student if they are vaccinated, as the student is not required to share this information. In addition, due to the power differential between faculty/staff and students, asking students whether or not they are vaccinated may put them in a situation where they feel that they have no choice but to answer, even if they would prefer to not answer the question.