Dr Gabriel Scally says most young people are "very enthusiastic" about getting a COVID-19 vaccine, and they won't be taken in by false "stories and scares" about the jabs.
The public health expert was speaking as children aged 12-15 start getting their first doses across Ireland this weekend.
The first doses for the age group were administered yesterday, while most vaccine centres across the country will be focusing on appointments for teenagers this weekend.
Teenagers will get either the Pfizer or Moderna vaccines, and will need parental consent to get a jab.
Over 71,000 teenagers have registered since the portal opened for the 12-15 age group on Wednesday evening.
Dr Scally says it's a good day when you see so many young people signing up to get vaccinated.
He observed: “Young people are very enthusiastic, and their parents as well - they’ve seen the disruption COVID produces in their education, and undoubtedly they know people who’ve had it and not done very well with it.
“A lot of young people are used to vaccination, and are not going to be taken in by some of the absolutely dreadful, spurious stories and scares - I don’t think that will have any impact on young people at all."
Dr Scally said the virus doesn't typically affect children as badly as adults, but it can still have a serious impact.
He said: “Children and young people do get long COVID, even if very, very few end up in hospital or unfortunately dying because of COVID.
"And there are children who are vulnerable, and kids who need to be protected - the best protection they can have at school is being amongst a classroom who are also protected by the protection the vaccine gives.”
The HSE says it hopes to complete second doses for all teenagers in the 12-15 age group by the start of October.