INGERSOLL, ONT. -- The NDP is ramping up its call for a full public inquiry into how long-term care homes across the province have been so disproportionately impacted by the COVID-19 pandemic.

The call comes as the number of positive cases of the virus continues to grow at an Oxford County facility, the latest institutional outbreak in the region.

According to Southwestern Public Health here are seven positive COVID-19 cases at Secord Trails Care Community in Ingersoll, Ont..

What sets this outbreak apart from many others, is that none of the cases are among residents. All seven are staff members.

Although additional test results are still pending, none of the approximately 110 residents have currently been diagnosed.

Southwestern's Medical Officer of Health Dr. Joyce Lock told a media teleconferene on Friday that it began with one person testing positive Monday, and then by Friday morning there were six more cases.

The Secord Trails example underscores the challenges in contact tracing.

“Some had developed very mild symptoms prior to our first case, and so we don’t even know who the index case was or where the exposure may have occurred,” said Lock.

London-Fanshawe NDP MPP Teresa Armstrong, the party’s long-term care critic, continues to call for a full public inquiry into long-term care homes, rather than a government commission proposed by Ontario Premier Doug Ford.

Armstrong acknowledged Ford’s contention that an inquiry could take several years. She said if that’s the case, then recommendations can be implemented on an ongoing basis.

Armstrong pointed to a number of other high-profile inquiries in recent years.

“We’ve had inquiries under Ipperwash, Walkerton, SARS, Wettlaufer - and we’ve had thousands, thousands of people pass away. Residents in long-term care, staff, family members - and if this isn’t reason to call an independent, transparent public inquiry where people can have confidence in the process...”

The medical officer of health for the Middlesex-London Health Unit said Friday he too supports looking into what went wrong in long-term care.

But Dr. Chris Mackie couldn’t say which would be more effective, an independent commission or full inquiry.

“The most important thing to me is that the province is looking at this carefully,” said Dr. Mackie. “The attention that the premier is placing on the issue of what’s happened in long-term care is well deserved. The people in those facilities deserve that support and attention.”

- With files from CTV's Tammy Heisel