The spread of COVID-19 among children in England is fuelling a rise in cases - and concern among scientists that vaccines are being rolled out too slowly in schools.
Mixed messaging about shots for children, a later start and inflexibility with the roll out have combined to make vaccination for 12 to 15 year olds lag behind other European countries, scientists say.
Cases in Britain on the whole are higher.
A survey late last week suggested prevalence was at its highest level since January, with 8% of secondary school kids infected.
Lawrence Young, a virologist at the University of Warwick, warns that could risk the health of young and old alike.
"I think the other concern, the background of all of this, is the possibility of a perfect storm over the winter because we have got flu, we want flu vaccines to be rolled out in youngsters for the first time, that's all the way up to the 16-year-olds as well. With other respiratory viral infections, with all of what that means not only again for schools, but also for overwhelming the NHS... then the worry is that autumn and winter is going to get very very messy."
The goal was to offer all eligible children vaccination shots by the school half-term break, which starts next week.
Data released on Thursday (October 14) showed that 28.8% of children aged 12-17 had received a COVID-19 shot.
Part of the issue is that kids get their vaccines through schools, which has led to an uneven rollout.
The government is considering allowing them access to walk-in centers in the next few weeks.