VANCOUVER -- The union that represents prison guards at Mission Institution in B.C.'s Fraser Valley says it fears a second COVID-19 outbreak at the facility will be mismanaged by the Correctional Service of Canada.

Mission Institution was the site of Canada's largest outbreak of the coronavirus earlier this year. A total of 120 inmates - roughly 40 per cent of the prison's population - as well as a dozen staff members tested positive, and one inmate died.

On Thursday, the Union of Canadian Correctional Officers confirmed in a news release that two employees at the site have tested positive for the disease, adding that the Correctional Service of Canada "now describes the Mission Institution as an outbreak site."

CTV News Vancouver began reaching out to the correctional service for more information about the current COVID-19 cases at Mission Institution last weekend. On Tuesday, the service responded to confirm that there were two active cases of the disease among staff members there.

"We are monitoring this situation closely and diligently, and continue to apply our infection prevention and control measures," the correctional service said in an email statement. "CSC recognizes the importance of strong infection prevention and control protocols to contain the spread of COVID-19."

In its statement, the CSC described the incident as an outbreak, and said it declares outbreaks when there is reason to believe coronavirus transmission occurred in the institution.

In its release, the union said it "denounces" the decision of prison managers not to hire a professional cleaner to disinfect the facility after the two new cases were detected.

“There are currently two employees who have COVID-19. This leads to several tracing investigations and therefore the preventive isolation of several staff members,” said Derek Chin, president of the pacific region for the union, in the release.

“Mission experienced the largest outbreak of any penitentiary in the country this spring," Chin added. "We cannot understand why management will not take every precaution possible to prevent a further outbreak. Hiring a professional firm, like they did in spring, is one of them.”

The union also complained that the employer showed a "lack of transparency and seriousness" when investigating complaints from members about their safety from the coronavirus.

“No one wants to relive the nightmare of last spring," Chin said. "The employer must be serious this time around in its management of the crisis given the significant increase of community transmission of COVID-19 experienced in the Fraser Valley."

For its part, the CSC said in its statement Tuesday that it has continued to work with the union and public health authorities to put in place "extensive infection prevention and control measures" across all of its facilities.

"At this time, all staff at Mission Institution are required to wear both a medical mask and face shield throughout their shift, unless they are alone in an office or control post, or alone in an appropriate area for a meal break," the correctional service said. "All inmates are also provided medical masks at Mission Institution."

CTV News has reached out to the CSC for a response to the union's specific criticisms. This story will be updated when one is received.

The union isn't the only group that has been critical of the correctional service's response to COVID-19.

Rajinder Sahota, based in Victoria, is a partner at a firm that has launched a lawsuit against the Correctional Service of Canada for its response to the first outbreak at the Mission medium security institution in April.

Over the weekend, before the union had confirmed any positive tests for the virus, he told CTV News he was aware of a second outbreak at the facility.

Sahota said that the Mission prison should have been better prepared to handle the coronavirus pandemic back in the spring.

“In order to address their own systemic shortcomings when it comes to things like PPE, adequate staffing levels, having adequate protocols with respect to cleaning and distancing, the response was, amongst other things, just to lock down the institution and CSC is very, very well aware – or ought to be very well aware – of the long-term (and) short-term harms that arise from putting people into lockdown to deal with something (like a pandemic),” he said.

Now, he hopes that they don’t return to a lockdown again.

“If they resort to something like that again, then it's just an example of a problem that despite light being shone on it by the press and family members who were concerned, it's just not going to have any impact on the way they handle inmates unless there's some real consequences to that kind of behavior,” Sahota said.