There's an increasing outbreak including the death of a child too young to have been vaccinated. It's particularly prevalent in Bristol, Nottingham and Cardiff currently but it isn't much lower in other cities. I had a booster a month ago when I went for travel vaccines, my gp if offering it to everyone not vaccinated in the past 10 years as a precaution. I personally know half a dozen cases since Christmas and it's a town not a city.
For the young, elderly and immunocompromised this can be deadly and it's not very nice for everyone else, with a 3 week suggested isolation period, plus weeks of disrupted sleep.
Protect those unable to be vaccinated or those too young to have had the 3 doses.