Over 75,000 children aged 12-15 have registered for a COVID-19 vaccine so far, the HSE says.
More than 10,000 of those received their first dose yesterday - less than 48 hours after registration first opened for the age group.
Teenagers aged 12-15 are currently the last group set to be vaccinated, as no vaccines have yet been approved for younger children.
Vaccination for the 12-15 age group is continuing this weekend, with the HSE allocating "as many places as possible" at vaccine centres so teenagers get their first dose quickly.
Those in the age group will receive either the Pfizer or Moderna vaccines and will need parental consent to get their vaccine.
HSE CEO Paul Reid said many children and parents are now coming forward to get vaccinated.
Over 10,000 12-15 year olds administered a vaccine by Vaccination Centres & GPs yesterday, within 24 hours of registration. @HSELive
— Paul Reid (@paulreiddublin) August 14, 2021
He said: "Yesterday I witnessed many parents & their children from 12 to 15 attending a vaccination centre in Carrick on Shannon.
"Children have sacrificed so much in this pandemic too and they have shown maturity beyond their years.
"Vaccinations are our way out of this awful period."
Vaccinations are mostly taking place in the mass vaccination centres, although some GPs have also begun administering jabs.
Around 700 pharmacies across the country are now administering the Pfizer vaccine as well.
The HSE says it hopes to complete second doses for all teenagers in the 12-15 age group by the start of October.