The situation with chickenpox is actually quite complicated. The vaccine is not routinely offered in the UK. They say something interesting, which is that adul

The situation with chickenpox is actually quite complicated. The vaccine is not routinely offered in the UK. They say something interesting, which is that adults get a boost to their immunity whenever they are exposed to the virus (as most parents are). If children were vaccinated, then adults who had had chickenpox would not receive this boosting effect and it could cause a higher incidence of shingles in the adult population. Because chickenpox is mostly harmless in childhood, they reason that it's better to just hope that as many children as possible catch it, and vaccinate the adolescents that don't. http://www.nhs.uk/Conditions/vaccinations/Pages/chickenpox-vaccine-questions-answers.aspx#routineschedule http://www.nhs.uk/Conditions/vaccinations/Pages/chickenpox-v...