All the kids under 16 have a vaccination rate of 0% and they still count and they commingle and provide a reservoir. The vaccination rate in 16-25 year olds is also probably not high enough to achieve herd immunity with delta. It isn't a particular mystery why its still spreading unless you assume kids don't exist.

A single number for vaccination status and herd immunity would only be meaningful if the population was randomly well-mixed. In reality kids are much more likely to see other kids every day than hang out with the elderly.

We are rolling it out to 16-17 year olds, which happens to be the ages of my kids and both had their first shots about a week ago. There may be some marginal benefit for youngsters, but those dose are better deployed elsewhere. Over 17s are already well vaccinated here.

I'm not at all anti-vaccine, they've transformed the UK, but there's just no point vaccing under 16s. We're deep into diminishing returns with that, and those doses are sorely needed in many other countries.