Supply teachers will continue to move between different buildings and classrooms under the province's back-to-school plans.
That's despite COVID-19 standards designed to limit contact, including physical distancing for older grades and classroom "bubbles" for younger students.
Dr. Colin Furness, an infection control epidemiologist and assistant professor at the University of Toronto, says supply teachers could be a "weak link" in the plan.
"It kind of defeats the bubbling when you've got a group of people that are moving from place to place," he said. "That kind of mixing does exactly the opposite of what bubbles are supposed to do."
Occasionally, teachers are used to backfill permanent staff at different schools, frequently changing classrooms to piece together shifts. They face the precariousness of an unreliable work schedule and income.
The province also has permanent teachers and staff who typically travel among multiple schools, such as math specialists and speech-language pathologists.
Schools are expected to draft their own operational plans, which include safety and health standards when classes resume in September. New Brunswick districts contacted by CBC News said they are turning to the Department of Education and Early Childhood Development for guidance.
Anglophone South superintendent Zoë Watson said in an email her district employs a high number of casual staff to replace positions ranging from administrative assistants to custodians.
"In typical years, supply teachers are used to replace teachers who are out of their classrooms for meetings and [professional development] sessions," she said. "We expect the number of opportunities for these activities to take place will be very limited."
Watson said the details are still being worked out for the district's operational plan but will include protocols for anyone who enters buildings and buses. There will be specifics on mask use and contact tracing, and supply teachers will be offered a virtual orientation on the guidelines.
Department spokesperson Tara Chislett said in a statement that personnel travelling between schools will maintain two metres of distance. If physical distancing is not possible, community face masks will be used.
"They must also maintain a log of their movements, and districts will try to limit the number of schools that these employees visit," she said.
Those guidelines are in contrast to the standards for permanent teachers assigned to a class grouping in kindergarten to Grade 8. They will only be required to physically distance or wear a mask in common areas but can remove them when within their group.
For grades 9 to 12, physical distancing and wearing a mask when distancing is not possible will be required of all students and staff.
'It would definitely be safer'
The risk of transient employees has been studied in health care, where research shows they play a role in spreading infections between schools.
Furness said this evidence shows how staff travelling among many schools have the potential to spread COVID-19. He thinks the province should restrict the number of schools supply teachers can teach, while paying them for any difference in shifts.
"I think you need to really limit, so that supply teachers are assigned to a school or two, but not a whole ton of them," he said.
"There's no question it's going to be inefficient, but it would definitely be safer."
Furness also said there should be frequent testing of teachers and efforts to improve ventilation in schools.
Rick Cuming, president of the New Brunswick Teachers' Association, said it's important that training is provided for supply teachers on safety plans for different schools. He doesn't see itinerant and supply teachers as a risk because operational plans take them into account.
"They are going to adhere to the parts of the plan that ensure the safety, and that will be communicated with all the professionals that come in," he said.
Cuming said he believes the districts would have preferred to have supply teachers assigned to specific schools, even in normal times, since they have to adapt to many changes. But the numbers don't allow for it.
"In a perfect year, we would have assigned supply teachers and enough of them that they could just be dedicated to certain buildings in a time like this."
The New Brunswick Teachers' Association has been concerned about a shortage of supply teachers in recent years.
Cuming said recruitment has been a "chronic challenge," and he anticipates a greater need as teachers exhibiting symptoms stay home.
Teachers who feel slightly ill sometimes come into work, because of the effort required for putting together lesson plans, he said.
"That's really a habit that teachers are going to have to think about," Cuming said.
While districts are responsible for hiring supply teachers, Chislett said the Department of Education is working to support districts with recruitment given "a number of challenges" created by the pandemic.