If you don't know what HIPAA is, you need to spend time doing some research. It is a key part of a Benefits Specialist's job. Make sure your answer specifically points out that sharing the requested information would be in violation of HIPAA and discuss what you would do to help the manager instead.

"If a manager asked me for that kind of information, alarm bells would be going off in my head. That would be a huge HIPAA violation. I would let the manager know that I understood they were asking for the information to help their employees but that due to HIPAA, I am not able to provide them any type of information regarding who is enrolled in insurance. I would instead advise the manager to share the open enrollment information with everyone on their team. There could be insurance-eligible associates who aren't currently enrolled but want to, and some of your benefits, like your EAP, are available to all employees. So the materials and information for open enrollment should be shared with everyone as a group, not targeted only to those enrolled in health insurance currently."