The health secretary said offering vaccines by this date would allow teenagers to get some protection before starting school or college next month.
A walk-in site finder is being launched online by NHS England to help people locate their nearest vaccine centre.
Young people in this age group were first offered a jab earlier this month.
But unlike older age groups, no second dose is being scheduled.
They will be invited, by text or letter, to get vaccinated either by making an appointment through GPs or by going to a walk-in centre, the Department of Health said.
- What do young people need to know about the vaccine?
- Should all children get a vaccine?
- How many people have been vaccinated so far?
Tens of thousands of people aged 16 and 17 have already had the first vaccine. Having it done by 23 August will mean there are two weeks for them to build immunity before the new term gets underway.