The Health Protection Surveillance Centre (HPSC) said "this is more than would usually be expected" in Ireland.
The cause of the hepatitis in children is still unknown, and investigations are continuing to see if current or previous Covid infection may increase the risk of disease in some children.
None of the children with serious hepatitis had Covid-19 at the time. Investigations are also under way to see if there is any link to a surge in an adenovirus, which would typically cause a mild cold.
It comes as public health specialists are looking at what lessons can be learned from the Covid-19 pandemic so far.
A new study yesterday showed the incidence of Covid-19 has been higher among deprived communities compared with the better-off in Ireland, and they were also more likely to hospitalised.
The study was led by Dr Declan McKeown of the HSE's health intelligence unit, who said that along with his fellow researchers he wanted to look behind the "we are all in this together" mantra.
The evaluation examined the experience of people with higher levels of deprivation and the more affluent over three waves, from March 2020 to May 13 last year, he told the faculty of public health's summer scientific meeting at the Royal College of Physicians in Dublin.
Levels of deprivation were measured using the established HP Deprivation index, which includes demographics and social class.
The study looked at those who had a positive PCR test over that time before the wider roll-out of Covid vaccines. It found those from the poorer communities were more likely to catch Covid.
While they also had a higher chance of being hospitalised, there was no association between their background status and the likelihood of being admitted to intensive care or dying. Age and underlying health issues have been risk factors for hospitalisation throughout the pandemic, Dr McKeown pointed out.
However, the research on the impact of Covid across the social divide found the incidence was higher among people aged 20 to 39 in the better-off groups.
This could be due to more healthcare workers among their ranks, who would not only face more exposure to the virus but would be tested more frequently.
Overall, Dr McKeown said that given the data suggesting they were not more vulner- able to becoming critically ill and dying, the conclusion was that deprivation was not associated with "poor outcomes" in Ireland.
A separate presentation to the conference heard that counties in the Midlands saw a higher incidence of Covid at the end of December 2020 and the middle of March 2021.
Dr Mark McLaughlin, a medical officer in the Department of Health, said the cases were particularly high among vulnerable groups, including Travellers.
Covid testing hubs were set up, along with more vaccination centres. Testing take-up was relatively low, but they had more success in people coming forward for Covid-19 vaccination in early summer.
The conference also heard how the worry over side effects is resulting in some parents of young children aged five to 11 not allowing them to avail of a Covid-19 jab.
Public health specialist Dr Louise Marron said just over half of the parents questioned said they intended to vaccinate their children.
Of those surveyed, 28pc said they would not avail of the vaccine, while one parent in five said they remained unsure about whether their children should be vaccinated.
"There was no difference based on whether the child had chronic illness," Dr Marron said.
A higher intention to vaccinate was found in parents who believed Covid-19 could have a serious impact.