Public health officials are investigating another possible victim of meningitis following the recent deaths of three people from the deadly bug.
Eleven people were diagnosed with meningitis during a spike in cases since Christmas Eve.
The HSE revealed yesterday a possible 12th case is now being probed.
It comes as Health Minister Simon Harris and the HSE defended not extending the scheme to give a free vaccine, to protect against the lethal B strain of meningitis, to older children.
This is despite confirmation by the HSE that meningitis B was among the strains involved in the recent serious cases.
It is currently only available to children born since October 2016, forcing parents whose youngsters lost out to pay €280 for the jab.
Mr Harris said the HSE was guided by the recommendations of the expert group that advises on the roll-out of vaccines.
"I and the Government have implemented in full the advice of the National Immunisation Advisory Committee and I will be taking advice from nobody else in relation to vaccinations other than that committee," he said.
HSE public health specialist Dr John Cuddihy said yesterday that meningitis B mainly affects children under one year of age and they are now covered. None of the recent deaths were from the B or C strains.
The HSE said the surge in cases in recent weeks did not amount to an outbreak and there is no evidence one person was infected by another.
The cases happened in different counties among various age groups.
Different strains of meningitis were detected in the 11 cases diagnosed in recent weeks, including meningitis B, C, W and Y. There were 12 cases of meningitis W reported in 2017 and 11 last year. It can spread rapidly and cause serious illness in otherwise-healthy children and adults.
In the UK, young people starting university or college are offered the Meningitis ACWY vaccine, which protects against meningitis W and other strains.
However, this vaccine to protect against the W strain is not provided routinely by the HSE.
Parents who want increased protection for their adolescents must go to their GP to get it privately.
Dr Cuddihy said he is advising parents to ensure they are up to date with all the vaccines offered under the regular immunisation schedule.
"It is important that parents ensure their child completes all five sessions of the primary childhood immunisation programme," he said.
Dr Cuddihy said the cases of meningitis were relatively low.
"We were notified of 11 cases compared to five cases for the same period last year.
"The strains that have caused this meningitis are very varied."
He said there has been a dramatic decrease in meningItis C strain notifications and meningitis B cases over the years.
The expert advisory committee on vaccines looks at the numbers and they come up with the recommendations, he said. There is no indication that older children should be vaccinated for the B strain at the moment .
He said the meningitis W strain is very uncommon.
The experts review vaccine guidelines on a regular basis.
Overall he said the uptake of meningitis vaccines offered to infants could be a little better, particularly at the 12th and 13th month.
Last year, 89 cases of meningococcal disease were notified.
The speed of the disease makes it among the most frightening for parents.
Early diagnosis is essential and parents are urged to be familiar with symptoms, seeking urgent medical attention.
Symptoms include fever, joint or muscle pain, rapid breathing, severe headaches, drowsiness, discomfort from bright light, neck stiffness, vomiting, stomach cramps and diarrhoea. The Meningitis Research Foundation helpline is 1800 41 33 44.