Pharmacies and GP's may offer vaccines for 12 to 15 year olds as early as tomorrow.
The HSE's vaccine portal opened for the age cohort yesterday evening.
Appointments at vaccine centres for this weekend are being reserved for children.
Dr. Lucy Jessop from the HSE’s National Immunisation Office says parents must give formal consent for their child to be vaccinated.
"You must fill in your own contact details, but then all the other information is boast your child, including their PPSN.
"When you get an appointment text you also get a link back to consent, and it will give you the medical questions that you would have seen if you were an adult registering on the portal to make sure that the child is suitable is for the vaccine.
"It also asks you as the parent or legal guardian to give consent."