IRELAND has the highest incidence of the B strain of meningitis in Europe, with 58 reported cases in 2012. Children under five are the the most susceptible.
Around one in 10 children who contract this strain will die from complications. One of the children who was taken ill in Cavan has the B strain, and it is still unclear whether this form of the disease has also affected the other child.
It will prompt questions as to why the vaccine against this strain licensed last year is still only available privately.
The vaccine can be given to all age groups including infants from two months of age. The National Immunisation Committee, made up of experts who make recommendations on vaccines here, is still considering if it should be part of the jabs given to babies.
It is due to make a decision this year. It is examining concerns that immunity may wear off.
But the Meningitis Research Foundation in Ireland has called for its introduction.