The word 'flu' suggests to many people something akin to a rather heavy 'cold'. The truth is that, if you have the 'flu' (ie influenza) you will be very poorly, particularly if you are over 50. It is a very debilitating illness and it is highly unlikely that you would be able to get out of bed, let alone go to work. If the flu jab is available to you I would suggest that it would be very much in one's interests to have it.