Current policy in England is to offer a single dose of vaccination to all adolescents aged 12-17, basedon recommendations from the UK government’s Joint Committee on Vaccination and Immunisationand UK Chief Medical Officers that the direct benefits and risks from vaccination in healthy adolescentsare finely balanced, but there are wider benefits from reduction in educational disruption. The detailsand sources of the assumptions and analyses that form the basis of this recommendation from JCVIhave not yet been made publicly available, and what has been published did not assess benefits fromprevention of long COVID in children. Single dose vaccination for all 16-17 year olds has been offeredsince mid-August in England, which has meant that adolescents returned to schools in September2021 with at most one dose of vaccine. Here, we offer a quantitative risk-benefit analysis of 2 dosesof vaccination among adolescents based on two scenarios of high and low incidence of cases in 12-17year olds over a 16 week period. Our analysis shows that even with relatively conservativeassumptions, the benefit of vaccination in terms of hospitalisations in adolescents outweighs risksunless case rates are sustainably very low. Benefit of vaccination exists at any case rate for theoutcomes of death and long COVID, since neither have been associated with vaccination to date. Ourresults are robust to changes over time in case ascertainment and ascertained case to hospitalisationratios. Given the current (as at 15 September 2021) high case rates (600/100,000 population/week in10-19 year olds) in England, our findings support vaccination of adolescents alongside robustmitigations in schools.