Teenagers are slower to come forward for a Covid-19 vaccine than older age groups, with nearly one in three 16 to 17-year-olds yet to register for a jab.
igures from the HSE show 70pc of this group have applied for a vaccine and 8pc are fully vaccinated.
It comes as the countdown to the return to secondary school is under way amid fears the highly infectious Delta variant will inevitably lead to outbreaks next term.
A quarter of people aged 15 to 24 who are being tested are proving positive for the virus, indicating significant levels of infection among this group.
HSE chief Paul Reid said yesterday that some of those who had yet to apply for a vaccine were “under 18, whose parents and guardians are still weighing up the facts”.
Among 12 to 15-year-olds, he said 124,000 out of 275,000 had been signed up by their parents and 72,000 had been administered with a first dose.
Among the 18 to 29-year-olds, around 17pc have yet to register, with one in 10 people in their 30s still to apply for a vaccine.
The slower take-up among younger people has also been seen in other countries, although it is still relatively high here. So far, 90pc of the adult population are partially vaccinated with at least one dose and 83pc are fully covered.
Niamh O’Beirne, head of testing and tracing in the HSE, said she expected a high level of demand for testing in the early weeks of the return to school.
It comes as a British public health study has found that protection from either of the two most commonly used Covid-19 vaccines against the now prevalent Delta variant of the coronavirus weakens within three months.
It also found that those who get infected after receiving two shots of either the Pfizer-BioNTech or the AstraZeneca vaccine may be of greater risk to others than under previous variants of the coronavirus.
Based on more than three million nose and throat swabs taken across Britain, the Oxford University study found that 90 days after a second shot of the Pfizer or Astrazeneca vaccine, their efficacy in preventing infections had slipped to 75pc and 61pc, respectively.
That was down from 85pc and 68pc, respectively, seen two weeks after a second dose. The decline in efficacy was more pronounced among those aged 35 and older than those below that age.
“Both of these vaccines, at two doses, are still doing really well against Delta. When you start very, very high, you got a long way to go,” said Sarah Walker, an Oxford professor of medical statistics and chief investigator for the survey.
Ireland looks set to roll out a booster campaign from October once the first phase is completed later next month.
Mr Paul Reid said the National Immunisation Advisory Committee (NIAC) is expected to give advice next week. It looks increasingly likely the booster over autumn and winter will be confined to at-risk groups and not offered to the general population.
The evidence here so far is that the vaccines are dramatically reducing the risk of fully vaccinated people becoming very ill if they are infected with Covid-19.
Around 20pc to 25pc of people who are testing positive for the virus currently are fully vaccinated. Among hospital patients, most are unvaccinated and around 45pc are fully vaccinated.
People with underlying conditions whose immune systems are weakened are making up many of the fully vaccinated who are getting ill enough to be hospitalised.
Vaccination is leading to shorter hospital stays, and the average time spent in intensive care for all Covid-19 patients is around 14 days. But it can range from one to 97 days.
Prof Martin Cormican, HSE infection control lead, said people with underlying conditions who were fully vaccinated should enjoy the freedoms but avoid putting themselves at unnecessary risk. He said: “Fully vaccinated means you can do more of what is important to you with less risk to you and to everyone else.
“But there is still a need to observe the speed limits and think about the speed that is safe for you.”
The HSE will operate walk-in Covid-19 clinics for first and second doses over the coming days.
These clinics will be open to anyone in Ireland over the age of 16 who is not yet vaccinated or are awaiting their second dose. Details will be available on the HSE website.