More and more companies are requiring employees to be vaccinated as a condition of employment. The interviewer must make sure that you are willing to abide by company policy should this be required in the future. This is not a time to debate the vaccine's efficacy or bring up personal reasons for not taking it. If it is required as a condition of employment or is strongly encouraged by the employer, then you will need to have this information so that you can make a decision about pursuing the position further.