The flu virus has contributed to the death of a second child this season, it has emerged.
The latest death was an 11-month-old baby in the South Eastern Health Board region.
The Irish Times has learned that the death occurred last month but was only recently confirmed to the National Disease Surveillance Centre. The child also had meningitis.
This fatality follows the death, also last month in the South Eastern Health Board region, of an 18-month-old boy from flu.
The NDSC has again urged people in high-risk categories to be vaccinated against the flu. These would include children, people with asthma or heart conditions, chronic lung disease and diabetes, and those with lower immunity as well as those aged over 65.
According to the NDSC clinical microbiologist, Dr Robert Cunney, there are three main types of influenza - A, B and C - but influenza A generally causes the most severe form of the disease. However, deaths from it are rare.
The main strain circulating in the Republic is an influenza A (H3N2) Fujian-like strain, and it is this strain which is being blamed for the deaths of the two children. While the current flu vaccine does not offer full protection against the new strain, it is likely to give significant protection, the NDSC said.
Dr Cunney said the symptoms of influenza infection usually develop over a matter of a few hours and include a high temperature, sore muscles, dry cough, headache and sore throat.
"This is different from the common cold, which tends to come on more gradually and usually includes a runny nose and a normal temperature. Persons who are in one of the high-risk categories should contact their GP if they develop influenza symptoms," he said.
Most cases of influenza A in the Republic this season have been in the under-four age group.
"Detection of influenza in younger age groups is not unexpected as there has been very little influenza in circulation for the last few seasons, therefore the opportunity for development of immunity has been limited," according to the NDSC's latest weekly flu report.
It notes that during the past week absenteeism in a number of schools in the south-east increased, and admissions to at least one hospital in the region with respiratory illness also increased.