LONDON, ONT. -- Once considered the epicentre of the COVID-19 pandemic in long-term care homes in southwestern Ontario, Sarnia-Lambton is now fighting another seniors' home outbreak.

Lambton Public Health confirms there are now 29 positive cases at the non-profit Vision Nursing Home in Sarnia. Fifteen are residents and 14 are staff. There have been four deaths.

It’s by far the largest of three current institutional outbreaks in the city and Sarnia Mayor Mike Bradley said the community has been devastated.

"Why aren’t we defeating this is the question. We’re doing everything else we can to get people to socially distance, to protect themselves, and we have now become the focus on the loss of life. Nineteen people now in Sarnia."

There are also smaller outbreaks at Marshall Gowland Manor and St. Clair Retirement Home.

The most recent major outbreak was at Landmark Retirement Village, which has since been cleared up.

Lambton Medical Officer of Health Dr. Sudit Ranade said he continues to favour the tried and true practice of isolation rather than relying on testing.

"The most important thing too, in a long-term care setting, is that anyone who has symptoms should be proactively placed under precautions so you’re not waiting for that test to decide whether somebody should be placed under precautions when the test result comes back. You’ve already done it. You’ve been doing the right thing since you took the swab in the first place."

In the meantime, the provincial government is planning a probe into long-term care homes and how they have been devastated by the COVID-19 pandemic.

In Middlesex-London, which has its own share of institutional outbreaks, Medical Officer of Health Dr. Chris Mackie said he welcomes the investigation.

"This is a segment of the population that doesn’t have a lot of options in terms of where they live and how they live their lives. And I think if the province can turn some attention there and make sure they are being cared for safely, I think that’s a real positive."