There has been at least one confirmed Covid-19 case in all of NI's 39 special schools since the start of term.
That is according to the latest information published by the Public Health Agency (PHA).
About three-quarters of the 126 Covid-19 cases reported by special schools to the PHA were among staff.
The PHA figures also show there were more than 140 "incidents" in all schools in the week pupils returned after the extended half-term break.
An incident can be a single positive case, a cluster of two to five cases or more than five cases.
A cluster is defined by the PHA as two or more laboratory-confirmed cases of Covid-19 among individuals in one setting, such as a school.
The PHA has been informed of 2,420 positive Covid cases in schools since the beginning of term in August until 8 November.
There had been 812 Covid-19 incidents in 625 schools up until that date, said the agency.
The pre-school sector was the least affected, with positive cases in only about 10% of 458 pre-schools.
By contrast, almost nine in 10 post-primary schools and all 39 special schools had at least one positive case.
Six special schools had clusters of more than five cases, while 76 post-primary schools had similar clusters.
A total of 365 primary schools out of 805 in Northern Ireland had at least one case up until 8 November.
Derry and Strabane was the council area with the highest proportion of schools affected.
According to the PHA figures, less than 0.5% of pupils in Northern Ireland's schools have tested positive for Covid-19 since the start of term.
However, a number of other pupils or staff may have to self-isolate if they are in close contact with a positive case.
Some pupils have already had to self-isolate for a 14-day period more than once.
Separate attendance statistics from the Department of Education (DE) show that about one in every 50 pupils (2.1%) in Northern Ireland was recorded self-isolating in the week after half-term.
However, that was a significantly lower proportion than the week before the break.