SUDBURY -- North Bay health officials continue to investigate a COVID outbreak at a long-term care home after conflicting expert opinions following 13 staff members testing positive for the disease.

The North Bay Parry Sound District Health Unit declared a COVID outbreak at Cassellholme on Friday after more than a dozen employees and essential visitors from the facility tested positive on Feb. 16 during routine surveillance testing, including one person with a positive result for a COVID-19 variant of concern.

Over the weekend, Cassellholme said on its website that 10 essential caregivers who had received positive results are being reassessed and that seven had retested negative.

"The residents these people care for were immediately moved into isolation and tested. All have been confirmed negative for COVID," said the statement on the care homes website dated Feb. 20. "Two staff members received positive, low COVID detection results during the same time. Both have been retested as negative."

Because of the outbreak, no one can enter the facility, including essential caregivers who have negative COVID test results.

On Monday, the health unit sent out a news release to clarify the details of the outbreak.

"The health unit is consulting with experts in laboratory medicine and infectious disease regarding the COVID-19 test results of some of the individuals who tested positive. We have received conflicting expert opinions as to whether these tests were truly positive," said the health unit. "Based on the Ministry of Health’s COVID-19 guidance, it is not appropriate to clear an individual of COVID-19 based on a re-test alone, however, the peculiar circumstances at Cassellholme over recent weeks warrants further study."

Regardless of the results of the investigation, health officials said Cassellholme will remain under the outbreak designation because a COVID-19 variant of concern has been detected within an essential caregiver who has had symptoms and was at the facility during their infectious period.

Health officials said this individual's test results is not a false positive.

There are also several other reasons for the outbreak declaration to stay in place based on asymptomatic individuals who tested positive are connected to those experiencing COVID-19 symptoms, original COVID-19 test result data, and the Ministry of Health's case management requirements.

"(The health unit) assesses the risks involved with each positive result individually using the Ministry of Health’s COVID-19 guidance and public health expertise and judgement. Individuals who have met the Ministry of Health’s guidance requirements are counted in our case numbers until more information is available. Our case numbers reflect the correct number of known individuals who have tested positive for COVID-19," the health unit said.

Casselholme said staff are working hard to care for residents during this difficult time.

"It is unsettling, to say the least, that we find ourselves in this outbreak situation. Let's continue to support one another and stay safe," the long-term care home said. 

As of Monday afternoon, there were 30 active COVID-19 infections in the North Bay Parry Sound District Health Unit area. Only four of those are in the Parry Sound District, while the remaining 26 are residents of the Nipissing District. Four people with active infections in the district are currently hospitalized.

There have been 28 preliminary positive variant of concern cases confirmed and one strain, B.1.351 that originated in South Africa, has been identified in the community. This case involved a man connected with the Lancelot Apartment outbreak who died of COVID-19 last week.

The Lancelot Apartment outbreak has infected 35 people and in 26 of those cases, a variant of concern has been detected. As of Monday, 12 infections connected to the apartment complex remain active.

Since the pandemic began, the North Bay Parry Sound area has had 261 positive COVID-19 cases, 231 have been resolved, including two COVID-related fatalities.