[Margaret Pilkington]

This was always likely to happen.....and this is why the flu vaccine has to be given every year.
Every year the flu virus mutates and the vaccine is made to cover the viruses that were prevalent in the previous Southern Hemisphere winter....which is why their actions are sometimes less effective in preventing the flu here....by the time it gets here it has mutated further.
So the flu vaccine might protect you, but then again it might not.....a bit like playing roulette.

To take sensible precautions to protect yourself during the flu season is what is required....wash hands, vit D...vit C, alcohol/ chlorhexidine mouthwash as a gargle....will all help.
Masks do not, because as previously noted, the virus is too small to be captured by any mask on the market for the general public.
But then we have been here many times before.....we are going to have to live with this, much as we do with seasonal flu.