Sending teachers back to work without COVID-19 vaccines has the provincial union clanging alarm bells over the safety of its members.

On Wednesday, the Newfoundland and Labrador English School District announced it would heed calls from parents and students to open high school classrooms once again, after a variant outbreak at Mount Pearl Senior High infected dozens, including teachers, in February.

Dean Ingram, president of the Newfoundland and Labrador Teachers' Association, says there aren't enough safeguards in place to ensure it won't happen again: Two metres between desks, he says, doesn't translate to physical distancing compliance in the hallways.

"Anyone that's been in the school system knows that the cohorts break down very quickly," Ingram said. "Visit any school and just observe what happens in the interaction with students during the non-structural times."

Students at more than 50 high schools across the province have spent two months learning exclusively from laptops, isolated in their basements and bedrooms. That's led to slightly increased absenteeism, according to district data, and rampant complaints from parents and teenagers who feel they're not getting a fulsome education.

Education Minister Tom Osborne said Wednesday he was also warned by doctors of the risks of isolation on students' mental health.

In response, the province and school district developed a "blended" learning model, in which kids switch between in-person and online classes on alternate days. That keeps transmission risk low while attenuating the distance-learning concerns, Obsorne said Wednesday.

That model begins April 14, filling high schools to half their normal capacity.

But that hasn't satisfied all NLTA members. The last outbreak showed "how fragile our situation is," Ingram said. About 15 teachers from Mount Pearl Senior High contracted the illness in February as the virus ripped around the school. One of those members is still reeling from long-term effects, he said.

Ingram — who's careful to say it's not clear whether all those teachers came down with COVID-19 in the workplace — is nevertheless pushing to have teachers placed high on the priority immunization list to prevent it from happening again.

The Department of Health released an immunization timeline earlier Thursday. In it, teachers are grouped with other essential workers, and slated to sign up for their first doses of vaccine at the end of April.

Ingram also aired worries over staff getting pulled in all directions, trying to split their attention fairly between constantly-rotating online and in-person groups.

"It's got to be an effective environment," he said. "The fact of the matter is teachers cannot be doing two tasks simultaneously."

He's not alone in that concern.

Shelley Morse, president of the Canadian Teachers' Federation, says the province's new blended teaching model raises eyebrows at first glance, calling the demand for their divided attention "impossible."

Morse stressed the importance of figuring out distancing and ventilation in schools to get kids back to class, where they have resources and connections. That could mean finding unused office buildings and other spaces to create temporary classrooms, she suggested, spreading out the students.

In the absence of space, Morse said, the next step is rapid vaccination.

"We know that teachers want to be back in school," she said, "and they know that that's where the best learning takes place."