Meningitis B vaccines will be offered to year 11 pupils at schools affected by the Kent outbreak.
NHS Kent and Medway said on Tuesday that 10,627 vaccines had been given out.
The meningitis outbreak, which left two dead, peaked on 13 March.
On Monday, 20 cases of meningitis had been confirmed, with a further three under investigation, bringing the total to 23.
This was down from 29 on Sunday, when 20 cases were confirmed, and a further nine were under investigation.
Officials started vaccinating University of Kent students on 18 March.
The following day, on a visit to the campus, Health Secretary Wes Streeting said the programme would be expanded to more people, including sixth form pupils at four schools with known or suspected cases of menB.
Meningitis outbreak: Number of cases falls for first time
Meningitis outbreak: Total cases in Kent rise to 34 as over 8,000 vaccines handed out
Meningitis could spread outside Kent in ‘most likely’ scenario, says health official
Experts at the UKHSA have been investigating the “unusual” outbreak.
They looked at three possibilities: the strain; immunity of the affected population; and social factors.
The UKHSA has stated that “it is highly likely that all three factors are contributing,” but that it is a “realistic possibility” that the strain is the “main driver”.
Be the first to get Breaking News
Install the Sky News app for free
Officials confirmed last week the strain behind the outbreak belongs to a group of bacteria known as group B meningococci, with a recently emerged subtype that has been present in England since 2020.
However, the UKHSA suspects the genome of the bacteria has “multiple potentially significant genetic differences”.
The UKHSA also confirmed the people affected have a median age of 19, and while the majority are in education, five are not students.
Read more from Sky News:
Transgender girls given until September to leave Guides
Adolescence dominates BAFTA TV Awards nominations
Of those affected, 87% attended Club Chemistry in Canterbury at least once between 5 March and 7 March before becoming unwell.
Most of those were students, and the three cases who did not go to the nightclub are all University of Kent students living in halls with links to those who did attend.
Professor Robin May, chief scientific officer at UKHSA, said that “preliminary analysis offers strong reassurance” that existing vaccinations and antibiotic treatment are “effective against this strain”.
