The interviewer wants to know that you are a reliable person. Tell the interviewer that you are reliable and do not 'accidentally' miss a shift. Next, share with the interviewer how few times you have called off from work in the past year. If you were sick with the flu and had to call off work 2 days in a row, that's to be expected! Simply tell the interviewer that you had the flu and had to call off 2 days in the past year. We are all human and get sick from time-to-time. Missing work for those 2 days will not be a deal breaker.