The Health Service Executive has written to schools and childcare providers advising them that children with fever, cough and sore throat should be kept home to combat a "significant increase in viral infections" and amid concerns about Group A Strep.
The letters advised that "there has been a large increase in general viral infections among children and young people this winter. There have also been recent concerns about a rare bacterial infection... iGAS... also known as Group A Strep".
It said that "Ireland has seen cases of more serious (Group A Strep) infections recently", but said that "so far the rate of serious infection is below the level seen before the Covid-19 pandemic".
The letter said that "the most important measure" was for children to stay at home if they have "fever, cough, and sore throat".
It also stressed the importance of infection prevention and control measures such as covering coughs and sneezes and keeping hands clean, and of keeping up-to-date on all recommended vaccinations.
It said that while there is no vaccine against Strep A or many other viral illness, other vaccinations would make them less likely to be unwell if they do get an infection.
This evening, the HSE confirmed that a child under five had died from Strep A infection. It said that Local Public Health is supporting the family and the school attended by the child.
Dr Éamonn O'Moore of the HSE Health Protection Surveillance Centre (HPSC) said: "The news of a child death with Strep A will be worrying for parents, but it's important to know that most children who get ill from a Group A Strep infections will have a mild illness which can be treated with antibiotics."
Chief Medical Officer Professor Breda Smyth said Strep A was quite common, but can give rise to serious illness.
Speaking on RTÉ's Morning Ireland, she said: "What we do know is Strep A is quite a common infection. For the most part it can give rise to a mild illness but in a rare number of cases it can develop invasive Group A Strep and give rise to significant illness," she said.
She added: "We do also know that because it is such a common bacteria, 20% of us in the population actually walk around with it in the back of our nose or in our throat, and it may not affect us at all, however it can give rise to mild infection such as skin infections and throat infections, and it is treatable with antibiotics.
"However, in a small number of cases it can go on to develop more severe infection".
Asked whether preventative antibiotics measures could be used, Prof Smyth said that if there is a Strep A case in a school, a local public health team would carry out a risk assessment before deciding an appropriate course of action.
"There are a number of elements that would be taken into consideration, the number of cases within the actual assessment and also whether there are other symptomatic cases of Strep A in the classroom," she said.
Prof Smyth said that during the pandemic the circulation of the bug reduced, and so there were not as many cases.
"The number of cases we have had this year is actually much lower than pre-pandemic times, but we are keeping a very close eye on it, as we know there are a lot of bugs circulating at the moment. Because we had reduced social mixing particularly in children, we are seeing a lot of illness at the moment with RSV," she said.
The CMO said parents should be mindful of symptoms, but also trust their own instincts if their child is not well and not responding to treatment.
"I would always say to parents to trust your instinct, and if you feel your child isn't getting better with routine responses, then it’s important to contact your GP or health professional," she said.
Asked if children were now less developed to cope with circulating viruses because of two years of Covid-19 restrictions, she said reduced social mixing meant children were less exposed to such illnesses, and that this in turn was why there was such "exaggerated responses" to what she termed "a constellation" of bugs circulating at the minute.
Prof Smyth also gave an update on vaccine uptake for flu, saying it was "very positive" among over-65s, and last week stood at over 70%.
She said, however, that their target is 75%, and urged people to come forward for it.
"I would urge people who are appropriate for the booster to also get their Covid booster, because with increased positivity that would indicate we are seeing an increase in Covid cases also, and these are all things that will put pressure on our healthcare system," she added.
Meanwhile, the HSE has said that GPs and hospitals have been asked to be alert to the symptoms of Strep A infections.
HSE Chief Clinical Officer Dr Colm Henry told the Joint Oireachtas Committee on Health that Strep A is a common bug usually seen in the spring or summer.
He said that Ireland has seen, in line with the UK experience, an increase in cases, particularly in relation to the invasive group A Strep.
It may be explained by more mixing of people in the post-Covid era and altered immune patterns for people who have not been mixing as much as they should, he said.
He told the committee that the Health Protection Division in Public is meeting today and has already sent alerts to GPs and to hospital practitioners increasing awareness and alertness for the symptoms and signs.
He also said the HSE would consider antibiotic use in certain circumstances where there have been cases.
Additional reporting Fergal Bowers and Will Goodbody