Principals have reported significant problems hiring substitute teachers to plug staffing gaps as some schools prepare to reopen this week.
A survey of 124 secondary schools highlights how 98pc of respondents said they faced difficulties hiring substitute teachers in the past 12 months.
"This will undoubtedly pose problems in the coming months should the need [to hire substitute teachers] arise due to absences, and there will be a need for funding from the Department of Education," Adrian Power, president of the Principals and Deputy Principals Association (PDA), said.
The survey, carried out by the PDA and Teachers' Union of Ireland (TUI), cited pay discrimination as a significant barrier to recruiting staff.
It also found that nearly half of schools had issues finding builders and contractors to carry out the necessary works to enable social distancing.
The Irish Independent previously reported how some schools faced delays in reopening, as they were obliged to engage in a tender process for any building work. Schools had to obtain three quotes for any minor works needed and retain documentary evidence, whether received in writing or over the phone.
"By their very nature, schools are innovative places, but the recalibration of classrooms and buildings has proved massively challenging, so it is likely that some schools will require flexibility in terms of opening dates," Mr Power said.
"The preference of teachers has always been a return to face-to-face teaching... but this must, of course, be done in a safe manner."
The online survey was carried out last week. Along with concerns about hiring new teachers due to absence levels caused by Covid-19, many principals said they were worried about the health of some staff.
More than 70pc of principals who took part in the survey said they were aware of staff who lived with family members with underlying health issues, and 66pc said they have teachers in the high-risk category.
TUI general secretary Michael Gillespie said: "The survey findings highlight most schools will have teachers with underlying health issues that put them in the high-risk category and also teachers who live with family who have underlying health issues making them vulnerable in terms of Covid-19.
"Our members have a range of justified concerns in this regard and we will continue to raise them on an ongoing basis with the department."