Why does the US vaccinate against chickenpox but the UK does not?
And why is the HPV vaccine available for boys and girls in the US, but is currently only offered to girls in the UK? ( In July 2018, the UK announced it will make the HPV vaccine available to boys, but with no current start date. )
Referring to the article in this link https://www.nhs.uk/common-health-questions/childrens-health/why-are-children-in-the-uk-not-vaccinated-against-chickenpox/, UK views chickenpox as a mild illness and rather more concerns about the possible consequences, such as adults getting more severe and dangerous chickenpox, if all children get chickenpox vaccination. Therefore, UK does not encourage all of their citizens to have chickenpox vaccination.
I am not quite sure about the reason why England offered HPV vaccine only to girls, but I found a news that they are going to extend the vaccine to boys to prevent diseases such as throat, penis, anus and other types of cancers. This is the link for the aricle about the changed policy of UK HPV vaccine: https://www.newscientist.com/article/2174940-hpv-vaccine-to-be-offered-to-all-children-in-england-not-just-girls/