55 it's not a strain as such, it's a piece of the virus that your immune system can recognise as foreign and produce antibodies to attack it when you come into contact with the intact virus. If mutations continue to express the said piece then we're ok, if it changes or can mask itself into something the body cannot detect and has the same virulence or worse then it's back to square one.

All vaccines carry a risk which has to be considered against the risk of not having it, in my view the latter is worse - more of us now are starting to hear of tales close to home of healthy younger individuals who have died.